Re-enable SaveGameFixer and improve it to also run on canned stock craft dirs

These commits re-enable the SaveGameFixer, add functionality necessary to operate outside the "saves" dir, and adds update runs on the canned "Ships" dir that ships with KSP.

I've done nominal testing only on a lightly modded install: game loads without exception, Kerbal X loads up, DecoupleForX64 and TweakableDecouplers play nicely together, ship flies, decouplers work.