Qt's built-in QAudio calls rather than PortAudio. Also includes some
refactoring of the arrangement for these calls, and more use of C++ style.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@3523 ab8295b8-cf94-4d9e-aec4-7959e3be5d79