Refactor Feature name management and creation:

* Only require adding the new feature names in one place. (Also need to
  increment a counter, but a check on startup will catch that.)
* Allows rippled to have the code to support a given amendment, but
  not vote for it by default. This allows the amendment to be enabled in
  a future version without necessarily amendment blocking these older
  versions.
* The default vote is carried with the amendment name in the list of
  supported amendments.
* The amendment table is constructed with the amendment and default
  vote.

src/ripple/app/main/Application.cpp

@@ -1250,27 +1250,29 @@ ApplicationImp::setup()
 
     // Configure the amendments the server supports
     {
-        auto const& sa = detail::supportedAmendments();
-        std::vector<std::string> saHashes;
-        saHashes.reserve(sa.size());
-        for (auto const& name : sa)
-        {
-            auto const f = getRegisteredFeature(name);
-            BOOST_ASSERT(f);
-            if (f)
-                saHashes.push_back(to_string(*f) + " " + name);
-        }
-        Section supportedAmendments("Supported Amendments");
-        supportedAmendments.append(saHashes);
+        auto const supported = []() {
+            auto const& amendments = detail::supportedAmendments();
+            std::vector<AmendmentTable::FeatureInfo> supported;
+            supported.reserve(amendments.size());
+            for (auto const& [a, vote] : amendments)
+            {
+                auto const f = ripple::getRegisteredFeature(a);
+                assert(f);
+                if (f)
+                    supported.emplace_back(a, *f, vote);
+            }
+            return supported;
+        }();
+        Section const& downVoted = config_->section(SECTION_VETO_AMENDMENTS);
 
-        Section enabledAmendments = config_->section(SECTION_AMENDMENTS);
+        Section const& upVoted = config_->section(SECTION_AMENDMENTS);
 
         m_amendmentTable = make_AmendmentTable(
             *this,
             config().AMENDMENT_MAJORITY_TIME,
-            supportedAmendments,
-            enabledAmendments,
-            config_->section(SECTION_VETO_AMENDMENTS),
+            supported,
+            upVoted,
+            downVoted,
             logs_->journal("Amendments"));
     }
 

src/ripple/app/misc/AmendmentTable.h

@@ -22,6 +22,7 @@
 
 #include <ripple/app/ledger/Ledger.h>
 #include <ripple/core/ConfigSections.h>
+#include <ripple/protocol/Feature.h>
 #include <ripple/protocol/Protocol.h>
 #include <ripple/protocol/STValidation.h>
 
@@ -36,6 +37,19 @@ namespace ripple {
 class AmendmentTable
 {
 public:
+    struct FeatureInfo
+    {
+        FeatureInfo() = delete;
+        FeatureInfo(std::string const& n, uint256 const& f, DefaultVote v)
+            : name(n), feature(f), vote(v)
+        {
+        }
+
+        std::string const name;
+        uint256 const feature;
+        DefaultVote const vote;
+    };
+
     virtual ~AmendmentTable() = default;
 
     virtual uint256
@@ -168,7 +182,7 @@ std::unique_ptr<AmendmentTable>
 make_AmendmentTable(
     Application& app,
     std::chrono::seconds majorityTime,
-    Section const& supported,
+    std::vector<AmendmentTable::FeatureInfo> const& supported,
     Section const& enabled,
     Section const& vetoed,
     beast::Journal journal);