ENH: Update nlohmann/json from v3.1.1 to v3.2.0

List of changes:

$ Axel Huebl (2):
      CMake: 3.8+ is Sufficient
      Package Manager: Spack

Carlos O'Ryan (1):
      Fix trivial typo in comment.

Chuck Atkins (2):
      Make the CMake install dir user-configurable
      Enable target namespaces and build dir project config

Danielc (1):
      fixed compile error for #1045; to_json for iternation_proxy_internal was needed

Guillaume Racicot (10):
      basic_json now supports getting many type of strings
      Amalgamated headers
      Amalgamate single include
      Added test for conversion to string_view
      Added test for string conversion with string_view
      Disabled implicit conversion to string_view on MSVC 15.13 and older
      Set MSVC version from 1514 and older
      Re-added external_constructor with string compatible types
      Aligned template declaration
      Fixed check for compatible string type

Hyeon Kim (1):
      Add new JSON_INTERNAL_CATCH macro function

James Upjohn (1):
      Fixed incorrect version number in README

Jan Schöppach (2):
      Fix typo
      Fix typo in single_include, too

Julius Rakow (4):
      meson: fix include directory
      meson: add multiple headers target
      📝 link to cppreference via HTTPS
      📝 fix links to cppreference named requirements

Kevin Tonon (2):
      Using target_compile_features to specify C++ 11 standard
      Update CMake to latest on Travis

Matthias Möller (3):
      remove stringstream dependency
      typo
      added char cast

Michael Gmelin (2):
      Make section names unique in loops, as catch doesn't support duplicate sections, see also catchorg/Catch2#816 (comment)
      Exclude bytewise comparison in certain tests. These tests never worked - they weren't run before d5aaeb4.

Mike Bogdanov (2):
      pvs_studio fix. misprinted condition
      did make amalgamate

Niels Lohmann (125):
      ✨ added a SAX parser #971
      🔨 fixed test cases to be more robust
      ✅ added more tests for SAX parsing
      🔨 removed a logic error and improved coverage
      👌 fixed some compiler warnings
      📝 overworked README
      ♻️ refactored SAX parser
      🔨 added a SAX-DOM-Parser
      🚨 fixed a linter warning
      💚 fixed test case
      🔨 added error messages to SAX interface
      🔨 added SAX-DOM-Parser
      🔨 simplified SAX-DOM parser
      🔨 using the SAX-DOM parser
      💚 added regression tests for #972 and #977
      ♻️ refined SFINAE to fix some warnings
      💚 added another test case
      🔥 replaced acceptor with SAX parser
      👌 fixed some more warnings
      🔨 trying to fix the leak
      🔥 removing failing test (work on this in branch "leak")
      🚑 hopefully fixed the memory leak
      📝 cleanup after #1001
      👌 made changes proposed in #1001
      💚 improved test coverage
      ♻️ refactored binary readers to use a SAX parser
      🔨 cleaner exception interface
      📝 thanks for #1006
      ♻️ adjusting lexer/parser in symmetry to #1006
      🔨 fixed compilation error
      🏁 fixed an MSVC warning
      🏁 experimenting with /Wall
      🏁 moved /Wall to CMake
      ⏪ oops
      🔖 set version to 3.1.2
      🔖 set version to 3.1.2
      ♻️ implemented a non-recursive parser
      ✅ improved test coverage
      🔨 cleanup
      🚧 started a SAX/DOM/callback parser
      🔨 some refactoring
      ♻️ proper use of SAX parser for binary formats
      ✨ implemented non-throwing binary reader
      ✅ improved test coverage
      📝 updated documentation
      ✅ more tests
      ✅ improved coverage
      ✅ improved test coverage
      🔨 changed SAX interface
      🚑 fix for #1021
      🔨 improved code #1021
      🔨 realized callback parser wirh SAX interface #971
      📝 fixed example for operator> #1029
      💚 fixed Valgrind options #1030
      🔨 using a vector<bool> for the parser hierarchy
      🔨 cleanup
      🚧 added input adapter for wide strings #1031
      🔨 trying to make tests run with MSVC #1031
      🔨 trying to make tests run with MSVC #1031
      👌 fixed compiler warnings #1031
      ✅ improved test coverage #1031
      🔨 removing unget_character() function from input adapters #834
      🔨 cleanup
      🚑 fixed commit 1e08654
      💩 first try on #1045
      👷 added Xcode 9.3 builder
      📝 updated THANKS list
      🔥 removed commented-out test cases #1060
      📄 added SPDX-License-Identifier
      📝 added public key used for commits and releases
      🔧 update issue templates
      🔥 removed old issue template
      Update issue templates
      🔨 removed unget function for wstring parsers
      🚑 fixed error in callback logic
      ✅ added more tests from recent nst's JSONTestSuite
      ✅ adjusted test cases
      ⚡ keys are now returned as const reference #1098
      👌 mitigating cppcheck bug #1101
      🔨 only calculate array index string when needed #1098
      📝 added documentation
      🚑 adjusted Fuzzer to new parser
      📝 documentation to avoid future issues like #1108
      💄 cleanup
      📝 documentation fix
      📝 fix for #1052 #1139
      🚨 removed compiler warnings
      🚨 fixed more compiler warnings
      🚨 fixed more compiler warnings
      👷 tryping different platforms for AppVeyor
      🔨 small refactoring to improve branch coverage
      💄 fixed indentation
      👷 experimenting with AppVeyor and MinGW
      👷 forgot quotes
      👷 set build type
      👷 using help from https://stackoverflow.com/a/48509334/266378
      👷 forgot old PATH
      👷 trying a more recent compiler
      🔨 fixed escaping for MinGW
      👷 using Ninja to speed up build
      👷 choosing correct image
      📝 mentioned MinGW in README
      🔨 added macro to disable compiler check #1128
      🔨 cleanup after #1134
      📝 added note about CocoaPods #1148
      🏁 fix for #1168
      🚑 fix for #1169
      🏁 trying to fix C2440 error
      🏁 implicit conversion is not allowed with MSVC
      👷 added more CI workers
      👷 added more CI workers
      📝 updated documentation of used compilers
      🎨 reindented code
      🚨 fixing a MinGW warning #1192
      🔨 fixed a MinGW error #1193
      🚨 fixed some compiler warnings
      📝 overworked documentation
      🐛 fixed callback-related issue (nlohmann/json#971 (comment))
      🚨 fixed a compiler warning
      📝 release preparation
      ⬆️ Catch 1.12.0
      📝 added example for sax_parse
      🔖 preparing 3.2.0 release
      🔨 fixed amalgamation
      🔖 set version to 3.2.0

Sonu Lohani (1):
      Fixed compiler error in VS 2015 for debug mode nlohmann/json#1114

Théo DELRIEU (11):
      missing CHECK_NOTHROW in unit-udt
      support construction from other basic_json types
      Provide a from_json overload for std::map
      from_json: add missing template arguments for std::map
      from_json: add overload for std::unordered_map
      run make amalgamate
      split meta.hpp, add detected_t (used to define concepts)
      use templates in the sax interface instead of virtuals
      remove no_limit constant and default values
      use abstract sax class in parser tests
      add static_asserts on SAX interface

Tsz-Ho Yu (1):
      Fix -Wno-sometimes-uninitialized by initializing "result" in parse_sax

Vitaliy (4):
      test (non)equality for alt_string implementation
      define global operator< for const char* and alt_string
      forward declarations to make new compilers happy
      simplify templates for operators, add more checks

Vitaliy Manushkin (5):
      dump to alternate implementation of string, as defined in basic_json template
      dump to alternate implementation of string, as defined in basic_json template (changes to amalgamated code)
      forward alternative string class from output_adapter to output_string_adapter
      add unit test: checking dump to alternative string type
      test refactoring

Wilson (1):
      Make integration section concise

martin-mfg (1):
      fix typo in readme

SuperBuild/External_nlohmann_json.cmake

@@ -26,7 +26,7 @@ if(NOT DEFINED ${proj}_DIR AND NOT ${CMAKE_PROJECT_NAME}_USE_SYSTEM_${proj})
 
   ExternalProject_SetIfNotDefined(
     ${CMAKE_PROJECT_NAME}_${proj}_GIT_TAG
-    "v3.1.1"
+    "v3.2.0"
     QUIET
     )