Blender Git Loki

=== warnings cleanup ===

cleaned up some bad warnings and ugly stuff from not being careful enough in last commit.

especially these were dangerous:
interface_icons.c:716: warning: `return' with no value, in function returning non-void
interface_icons.c:779: warning: implicit declaration of function `waitcursor'
header_image.c:757: warning: implicit declaration of function `BIF_preview_changed'