the lethal pellet of a point-blank SSG blast

gets an extra damage boost for the occasional gib chance
add key to toggle always run

TODO: Caps Locks only sends a gamekeydown event on every second press
Vertical aiming is optional
Center automap markers on the map and fix a crash when a marker is outside the map

Closes https://github.com/fabiangreffrath/crispy-doom/issues/15
Closes https://github.com/fabiangreffrath/crispy-doom/issues/16