Merge pull request #30 from ranleung/assets

Assets
Fixed various sound bugs
Fixed help screen.
Merge branch 'masterfix' into evenMoreBugFixes
Fixed Swap powerup swap textures.
Merge pull request #31 from ranleung/evenMoreBugFixes

Even more bug fixes
Fixed powerup time interval.
Merge branch 'masterfix' into helpscreenassets
Merge pull request #32 from ranleung/helpscreenassets

Helpscreenassets
Merge branch 'masterfix' into assets