This improves our documentation for the gradle protobuf plugin, as its
version is dependent on the gradle version.
Gradle now has the --tests flag, performance improvements, and support
for OpenPGP subkeys.
This fixes a problem where gradle would try to use VC's amd64_x86 cl
(without the correct environment) and fail to compile with return code
-1073741515 (STATU_DLL_NOT_FOUND) because of missing mspdb120.dll.