Bug: Knockback can be used to move in midair

[minmay]

Knockback can move the party while they are falling or about to fall. This is problematic on levels with multiple elevations, especially with the Hand Cannon's special attack:
- It can be used to cross gaps by firing the special attack immediately after walking off a ledge, letting the party get places they shouldn't be able to
- If the party "lands" on another ledge while being knocked back, their world position will be off-center until they move (looks really weird)

[petri]

Thank you for the bug report! Added to my todo list for the next version.