1.6.0

This would technically qualify as a patch release. However, as the minimum required C++ version changed from C++17 to C++20 this is a minor version release instead.

Changes:

• Rename git master branch to main.
• Bump minimum required C++ version from C++17 to C++20 (0904b8c).
• Bump minimum required GPDS dependency version from 1.8.1 to 1.8.4 (f777d17).
• Fix leftover migration from QSchematic::Item to QSchematic::Items::Item (reported by @bjornstromberg) (416d973).
• Various minor internal code improvements.
• CMake
  • Fix an issue preventing the configuration where QSCHEMATIC_BUILD_STATIC=OFF and QSCHEMATIC_BUILD_SHARED=ON from compiling successfully (reported by @vowstar) (66a7cb1).
  • Introduce the CMake variable QSCHEMATIC_DEPENDENCY_GPDS_DOWNLOAD_VERSION which is passed to find_package(gpds) (778d829).
  • Previously, consumers were in need to create the CMake library aliases qschematic::qschematic-static and qschematic::qschematic-shared when consuming QSchematic in a superbuild scenario instead of via find_package(). From now on, QSchematic provides those library aliases itself (thanks to @bjornstromberg) (cc268b5).