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.
Accidentally left OptionsBinding.h out of previous commit.
Merge pull request #151 from kyzentun/player_options_fix

SongOptions Lua interface with the same design as the PlayerOptions interface.