´Revert "partial completion of crossfading of chainsaw sounds. THIS COMMIT IS BUGGY" too far gone to fix, taking another try at looping sounds with crossfades

This reverts commit 0cff31b6b4a2abb3f7a4fe6576787ce843c7d4c8.
added looped fade functionality to the idle sound. provides framework for doing it to the run sound, with the eventual goal of making it generic
final debug of idle looping, moving on to run looping
added looped fading for run sound. bug remains where if you click mousedown again during a rev up, or rev down, the game breaks