tests/src/io/test-source*.c: always get samplerate
tests/src/io/test-source_apple_audio.c: return error code
tests/src/io/test-source*.c: remove duplicate include
src/io/source_wavread.h: add native wav reader
src/io/source.c: add source_wavread
src/io/source_w*.c: disable debug output
README.md: improve
src/io/source_wavread.c: open file in binary mode for windows