Worked on Sprite and CentipedeSprite and related

Any changes in other classes were because I needed to access some data.
Entity interface modified.

Different entities were using different methods for getting bounds, etc. When making the gui, it was nessesary to have a standard interface.
standardized getting of the bounds
Worked on EntitySprites
Created visual tests and made gui modifications

The 'stubs' package contains subclasses that fill in enough code to get something to display. The CentipedeStub, for example, just returns random locations, and the board returns a few Centipedes.
Player movement works

Filled out stubs and gave Frame the keylistener instead of the panel
Invisible cursor
Bullet sprite was easy
Added mushroom sprite

Required adding a getHealth method to Mushroom. It is documented as to how it should be implemented to interface correctly with the sprite.
Abstracted checking for negative bounds to EntitySprite

Since every sprite does this check in shouldBeDrawn it was abstracted. See documentation for subclass implementation requirements.
Fixes for drawing of Mushrooms and Bullets

Tested them and they draw.
Code cleanup

removed unused imports
autoformatted everything in gui.
made not resizeable

also some code cleanup
Deleted some file git made