When using a MSBuild-based CMake generator like 'Visual Studio 15 2017
Win64', the doc build was failing with the error 'MSB6001: Invalid
command line switch for "cmd.exe". Illegal characters in path.'
This was due to the dependency on Doxyfile*, which wasn't expanded by
CMake.
The fix is to expand this glob in CMake before specifying the custom
command's dependencies.
Partial fix for https://github.com/miloyip/rapidjson/issues/622
* Support for both in-source and out-of-source builds
* Set library version to 0.12 to map Debian package
* Add separate options to build tests, examples and documentation
* Add pkgconfig lookup support (if installed with `make install`)
* Add CMake lookup support (if isntalled with `make install`)
* Add Google Test Source lookup
* Add CTest support for running tests (use `make test` or `ctest -V`)
