Use rock class for rocks.
Fix hud bug with negative health.
Disallow inventory access on player death.
Font tweaks.
Higher default resolution.
Allow all collidable objects to stop arrows.

Previously arrows would only collide with objects that had take_damage
methods.
More inventory information (bulk) displayed.
Collideable rocks that can also be picked up.

This means the player can use rocks as portable cover.
Objects are consistently dropped +y of the actor