Treadmill Right added, lots of code optimizing

Treadmill Right has been added, it uses the same image file as treadmill
left. Also a small bug was fixed with the treadmill, the player now
doesn't move when gravity is reversed and on a treadmill. Particles are
do no longer inherit GameObject to give particles less variables and
functions. All functions and global variables in main have been moved to
main_extra. This file may only be included by main AND NO OTHER FILES!
Also all the saw parts' direction variables are now in radiants, so
there is no converting from degrees to radiants.