Fix LÖVE SoundData generation

[tpimh]

The number of samples was off by one (not a big deal, but still).

LÖVE supports 8 and 16 bit samples, but they must be set as floats. So generate float samples first, set to SoundData later.

The last commit is just some minor optimization I did while I was at it.

Update: the default bit depth in generateSoundData and exportWAV functions was 0, but that was no longer the case. I fixed it and regenerated the docs.

This pull-request replaces #20 which should be closed.