Start work on inventory.
Fix get_bulk() bug
Draw debug touching circles around actors.
Items cannot be collided.
Add rock item for testing.
Switch arrow to using util.touching
Arrow have a fixed lifetime of 5 seconds.

After an arrow's lifetime expires, it disappears from the game.
Loading screen and fonts.
Add Human:drop() method
Add second rock for testing.
Font support in Actor

The Actor constructor can now take a LOVE2D image directly instead of a
string.
Prevent player from shooting after death.

The player can also now only pick up one item per mouse click.
Inventory system. Resolve #3

No category for money exists yet because I haven't decided how that will
be implemented in the game.