Implement sound fx pitch shifting

[drfiemost]

Since moving from fmod to sdl_mixer the functionality has been lost, Would be nice reimplementing it. See https://gist.github.com/hydren/f60d107f144fcb41dd6f898b126e17b2 for an example

[drfiemost]

The problem is that we call SoundManager.PlayWave with the new sample rate but we don't know the original frequency of the samples.
To make it work we should pass a resampling ratio instead to the PlayWave function.