* Add a level end screen that shows automatically when dead or level
is finished
* Lock player controls and GUI before the end screen shows
* Loop back to the main menu after finishing a level (or dying)
* Nerf combo chain score
* Add a placeholder KO animation for the player, and associated logic
Transitioning to the `next` animation frame preserved the priority,
which was a problem for enemies with a next: Hit=Idle or similar
transition, as that would give an infinite Idle loop with high
priority.
This change forces a clear of the animation priority when such a
transition occurs. This relies on the flawed linked list system, which
means that it will not happen if the new animation is just after the
current one in the source file. This is a fundamental issue due to
mixing all frames as single pointers in the anim_t structure. This will
be fixed in engine code eventually.
* Make all hitboxes rectangles
* Add sprite-based hitboxes for attacks, keep the original ones only for
map wall collisions
* Reorganize and rename animations
* Separate player movement and swing animation for the AoE