AudioLoader: use direct copy if there is no need to convert sample format
AudioLoader: use direct copy if there is no need to convert sample format

libavresample/libswresample should do that as well, however, having
direct copy in audioloader code will allow not to depend on this libraries
in case one is working only with 16 bit signed int wav files

ChristianFrisson/essentia,arseneyr/essentia,arseneyr/essentia,milrob/essentia,carthach/essentia,milrob/essentia,mrgloom/essentia,MTG/essentia,MTG/essentia,carthach/essentia,jjaner/essentia-musicbricks,jjaner/essentia-musicbricks,NadineKroher/essentia,mrgloom/essentia,arseneyr/essentia,milrob/essentia,MTG/essentia,NadineKroher/essentia,MTG/essentia,mrgloom/essentia,ChristianFrisson/essentia,jjaner/essentia-musicbricks,arseneyr/essentia,NadineKroher/essentia,NadineKroher/essentia,ChristianFrisson/essentia,carthach/essentia,carthach/essentia,carthach/essentia,MTG/essentia,ChristianFrisson/essentia,milrob/essentia,jjaner/essentia-musicbricks,milrob/essentia,arseneyr/essentia,mrgloom/essentia,NadineKroher/essentia,jjaner/essentia-musicbricks,ChristianFrisson/essentia,mrgloom/essentia