Add a new algorithm to calculate the true-peak. It implements the
Whittaker- Shannon interpolation from four samples to create 4
intermediate samples (5 x oversampling) inbetween the middle two
samples.

With 4 samples and 4 intermediate samples the algorithm can be
implemented as a 4x4 vector-matrix cross product, which is ideal for
SSE.

I've also replaced the sample-peak algorithm using SSE as well to
improve performance.

Closes obsproject/obs-studio#1189