Full functionality for stage 1 development.

This commit contains the full functionality for the following:

Player-enemy interaction
Weapon-enemy interaction
Homeless guy-Player interaction
Ability to obtain knife
Ability to free dolphin
Ability to get hamburger
Ability to feed homeless guy
Ability to kill enemy

TODO:
Add scrolling camera
Add more enemies and extend current code to support multiple enemies
(use List<>?)
Add boss stage
Add true hamburger and dolphin graphics