Created SongOptions Lua interface with a similar design to the PlayerOptions interface.  Moved enums that were inside SongOptions out and made them Lua accessible.  Removed sAutosyncType and associated things from AdjustSync.cpp because it was unused.  Added DefaultNilArgs and FArgGTEZero to LuaBinding as helpers.  Moved INTERFACE defines from PlayerOptions.cpp to OptionsBinding.h.