This was a leftover from the previous QMake options
but had no effect at all with CMake when enabled.
Distributions should use -DCMAKE_BUILD_TYPE='None'
to compile Mumble with the default compiler flags.
The existing `docs` directory was restructured a bit and the build
documentation previously located at
https://github.com/mumble-voip/mumble-releng-vcpkg was integrated into
the main repository (after having received a good polish).
In addition to that the needed scripts and port-files from the linked
repository have now also been included in the main repo.
