Added display list & double buffering management functions.
Tail call optimizations in long copy & set.
Call optimizations to bypass the entry table within the User Library.
Added surface management functions according to the work-in-progress specification.
Minor size optimizations in display list management.
Added missing us_dbuf_getsurface and us_dbuf_setsurface jump table entries.
Finalized version 00.013.001-00