[ Ilya Lipnitsky ]
* c_message.cc: Resolve name conflict between certain enums and oneofs
  (#427).
* protobuf-c.h: Fix Windows DLL export issue with the
  protobuf_c_empty_string symbol (#428).
* Standardize pkg-config for use by autotools and cmake, fix cmake tests
  (#425).
* protobuf-c.c: Cast %lu args to unsigned long int (#429).
* protoc-c: Remove leading underscores from structs (#430).
* protoc-c: Fix shared lib build on windows, migrate from Travis CI to
  GitHub Actions (#459).
* protobuf-c: Don't use ProtobufCWireType internally (#463).
* protoc-c: Add custom options support (#466).
* protobuf-c.c: Fix packed repeated bool parsing (#467).

[ Markus Engel ]
* Pack nested messages inline (#431).

[ Daniel Axtens ]
* Travis CI: Test on other platforms (#438).

[ Adam Cozzette ]
* Update the generator to fully qualify std::string (#443).

[ Piotr Pietraszkiewicz ]
* Install MSVC debug symbols alongside the protobuf-c.lib file (#456).

[ ihsinme ]
* Fix invalid unsigned arithmetic (#455).

[ Wolfram Rösler ]
* Avoid "unused function parameter" compiler warning (#453).