CMake + PortAudio

[jwinarske]

I implemented this last year. Open to changes.

Build Example on Linux:

mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=../bin
make -j

[googlebot]

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[googlebot]

CLAs look good, thanks!

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[Fleker]

Thanks for the PR, although this seems like too significant of a refactor to merge.