[Stk] RtAudio repository uploaded

[Stephen Sinclair]

Hi,

I've reconstructed a git repository history for RtAudio based on
previous releases and the RtAudio subversion repository on
SourceForge.

It's available here:

https://github.com/thestk/rtaudio

And tarball releases can be downloaded here:

https://github.com/thestk/rtaudio/releases

I meticulously went through svn history, comparing with the release
tarballs, and branched all tagged "release" commits in the releases
branch, fixing any inconsistencies.  (There were only a couple -- the
loss of Windows project files from 4.0.0 to 4.0.3, and the late
version change in 4.0.10's Makefile.in.)

I think this is good now, feel free to start using it!

I'll try to do the same for RtMidi this weekend, but it should be
quite a bit faster since there is no existing repository to compare
releases against.

I'll also do a couple of last fixes on my STK repository and upload it
to "thestk" github account.

Steve