some changes
	new file:   eZLib/nbproject/configs/Study.Friction.properties
	modified:   eZLib/src/eZLib/Geometry.java
	modified:   eZLib/src/eZLib/Physics/Body.java
	modified:   eZLib/src/eZLib/Physics/Friction.java
	modified:   eZLib/src/eZLib/Study/ForceSketch.java
	modified:   eZLib/src/eZLib/Study/FrictionSketch.java