Significant sound loop optimization.

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2762 86ba831e-150c-0410-ab35-e06eaae15ed9
Experimental reverb engine (not enabled in this commit; uncomment line in sound loop to play with it).

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2764 86ba831e-150c-0410-ab35-e06eaae15ed9