[AE] Rename ActiveAEResample to ActiveAEResampleFFMPEG
[AE] Move utility functions to AEUtil
[AE] Add factory for AEResampler
[rbp] Hardware accelerated resampling

This replaces the format conversion, up/down mixing and resampling code from ActiveAE with a GPU accelerated version.
Should significantly reduce CPU when using paplayer or dvdplayer.

Requires updated firmware
[resamplepi] Add GPU accelerated option to resampling options
[darwin] - sync xcode project
[win32] - sync project
Merge pull request #5479 from popcornmix/resample_factory

[AE] Add resample factory and Pi accelerated resampling