Merge branch 'winrt' into 'master'

WASAPI: Add paWinWasapiAutoConvert flag, which sets AUDCLNT_STREAMFLAGS_AUTOCONVERTPCM | AUDCLNT_STREAMFLAGS_SRC_DEFAULT_QUALITY for Shared mode streams.

Merged-on: https://assembla.com/code/portaudio/git/merge_requests/7481081