High Quality Resampler, using FIR filter

For more information:
https://docs.google.com/document/d/1tBEgsJh7QiwNwepXI0eobfK3U8LkJButSyeuFt1degM/edit?usp=sharing

removed: SSE includes (not used)

added: 16bit -> float -> 16bit functions
added: linear interpolator and high-quality (windowed-sinc) interpolator functions (including Resampler class)
added: dithering

changed: renamed variables and reformatted a few things to fit with style guide (braces, #include->const)
changed: use s16, u16, s32, u32 etc
changed: store samples and do all computations as floats
changed: volume from 0 - 255