Added force sun/thunder cheat.
Merge pull request #555 from duncanspumpkin/weather_cheats

Added force sun/thunder cheat.
Playing about with viewport setup
Add debug flag to dirty box draw
Added some more viewport functions
Added start of new function
Found cause of viewport issue. Added invalidate_sprite function.
fix custom strings not popping arguments
Merge pull request #556 from duncanspumpkin/fix_viewports

Fix viewports
fix string format, peep real names not popping arguments