Feature Request: More flexible build system

[pkrause1980]

1. Would it be possible to have a cmake project which includes the core, cli, plugins, etc.?
At the moment there are only two options (I'm on Linux):

• Calling cmake for each component manually, including the directory change, installing and so on.
• Using bootstrap.bash, which is really unnecessary complicated if something should be done differently. E.g., CMAKE_BUILD_PARALLEL_LEVEL is ignored because "make -j $(nproc)" is hardcoded, ccache cannot be easily activated via -DCMAKE_CXX_COMPILER_LAUNCHER and so on.

2. Avidemux cannot be build with another generator (-G / CMAKE_GENERATOR), except Make. Patching bootstrap.bash is trivial, but then this generator is wrongly used to built the included ffmpeg too.

Thank you!