Add support for reading WAV files containing ADPCM, A-law, µ-law, or 64-bit float data. (#449)

* Add ADPCM, A-law, and µ-law support.

* Add 64-bit float support.

* Fix clang-format violations in juce_PatchedWavAudioFormat.h

* Add missing float64 WAV file.

* Report accurate file_dtype for 64-bit float WAV; raise exception on read_raw()

* Add more tests and clarify some of the dr_wav code.