add ability to :map mouse buttons

[skrshe]

e.g.
hold middle click to pan map mbutton3 tool pan
use eraser on right click map/normal mbutton2 :brush/set erase {:brush/unset erase}
use accelerator buttons on gaming / special mice map mbutton8 :v/prev, map mbutton9 :v/next

extra:
draw with / use bg color on right mouse button down