Added yellow sprite for player 2
F4 toggles fullscreen; minor reordering of elements

F4 toggles fullscreen using object `obj_ctrl_fullscreen`.
Grouped all control objects in group `ctrl`.
Generalized `obj_ctrl_fullscreen` to all hotkeys
Added hotkeys for quit (Esc) and reset (F2)
Turned `obj_ctrl_hotkeys` explicitly invisible
Moved rim drawing to a separate object

Moved rim drawing functionality from `obj_control` to new
`obj_ctrl_rim`.
Moved draw objects to a separate group `draw`
Renamed `obj_ctrl_rim` to `obj_draw_rim`

This represents its functionality more properly.
Turned `obj_control` explicitly invisible
Set score display color to black
Refactor: controls are now handled in `obj_pl`
`update_speed` script: fixed `&&` conjunction
Players don't stick to walls anymore

Changed control method - doesn't use GM's `hspeed` now.