Updating the tracking code properly.

Hopefully this new code will track properly.
Fix entityState_t weapon bits if WEAPONNUM_BITS > 8

Add comment to make it somewhat more clear why not just using WEAPONNUM_BITS.
Merge branch 'master' into sdl2
Readd backspace char event for UI VM text fields

UI VMs expect a backspace char event, but sdl2 branch only was only sending a key event.
Revert cl_keys.c to master branch (it would cause backspace to happen twice in console).
Merge remote-tracking branch 'ioquake3/master'

Conflicts:
	README.md
Merge branch 'master' into sdl2
Merge remote-tracking branch 'ioquake3/sdl2' into sdl2

Conflicts:
	code/client/cl_keys.c