merge mukustes fixes branch

git-svn-id: svn://svn.code.sf.net/p/vpinball/code/trunk@913 14438d79-0ffd-4333-8ae7-ea2bdd901387
add uSleep routine

might be helpful later-on to limit very high FPS / give VPM more time / sync to a fixed FPS (physics)

git-svn-id: svn://svn.code.sf.net/p/vpinball/code/trunk@914 14438d79-0ffd-4333-8ae7-ea2bdd901387