Port increment_move radius clamps from Ring Racers

Fixes inconsistencies with thin players being able to thok through walls (see: Liftoff Gantry's small section), and with wide characters colliding with steep slopes instead of going up them.

changed milestone to %2.2.12

added Bug label

approved this merge request

merged

mentioned in commit 363faed8

added SRB2Kart port label

mentioned in merge request KartKrew/Kart-Public!360