Flip Tetris playfield upside down to match prototype
demo: Ignore exception for set_rgb_values on tab changes
demo: Unify handling for missing Bricklets
demo: Fix enumeration of Dual Button Bricklet
games: Close IPConnection properly on exit and deregister frame rendered callback

This avoids exceptions on exit.
text: Shift text one line down
text: Some unification between demo and example
text: Add random color mode
Add rainbow example
Remove unused files