Early code for Rock.cs
Merge branch 'master' into rock
Rock is ready to be added into level one. No animation.
Pre-offset drawing code.
Rocks drawing works with offsets.
Rock velocity & gravity is perfected.
Adds Up & Down arrow keys.
Claudy merged branch 'rock' into 'master'

Conflicts:
	Cliffhanger/Cliffhanger/LevelOne.cs
	Cliffhanger/CliffhangerContent/CliffhangerContent.contentproj