Change to javaw over standard java

Gives some users up to 10 more FPS in some cases and also adds optifine multi-core support to the game, javaw is what is used by standard minecraft so I don't think this will cause any issues I've tested it on a couple of windows machines and it worked fine, not sure about macs/unix but I assume it will be fine and yes I am aware of the fact that this literally changes 1 letter :3