Merge pull request #25 from tv-s/master

xaudio2 improvements
Work on resampler interface. Since resampler needs to look at a range of samples, we need to keep some of the previous samples around, too. Which is kind of a problem. Maybe limit these buffers to ~256 samples max and loop until done? Same history data could also be sent to filters.
Merge branch 'master' of https://github.com/jarikomppa/soloud
Small granularity audio buffers, mostly working: per-sample faders (at least) don't work, may have other issues too.
Per-sample volume fades added. There's still some slight error, probably caused by roundoffs of sample counts per buffer.
Upped the waveform sample rate.