Very minor cleanup (add comment, remove unused code), no functional change
Refactor function names for toggling the leds to be tasks (toggle_red_led -> task_red_led)
Added check for running the green task, added/removed some comments
Correctly clear register with mask (was previously just doing bit-wise and of all ones, which had no effect)
First version of USART files
Remove unused variables, added USART init stuff (haven't tested)
Fixed another comment typo