Create FixtureWrapper

To be used for holding convenience methods that are used often for
checking properties of a fixture (wraps Fixture class)
Pass FixtureWrapper instead of Fixture in multiple locations
Create listener for go button in DummyMenu

Actual behavior is unimplemented
Add getPlayer to FixtureWrapper

This seems like a cleaner way to handle getting the player if the
fixture is from the player. If you disagree, please discuss!
Merge branch 'develop' into gobutton

Conflicts:
	core/src/com/sweatyreptile/losergame/entities/Player.java
Functional GO button in the menu

Use fixture wrappers in order to call isPlayer() and getPlayer() on a
fixture

GO button establishes that the duck is quacking and in contact, then
calls level("test_home") to switch to the first level
Merge pull request #37 from SweatyReptile/gobutton

Functional GO button