some changes
	new file:   eZLib/nbproject/configs/Study.BouncingBall.properties
	modified:   eZLib/src/eZLib/Geometry.java
	modified:   eZLib/src/eZLib/Sketch.java
	new file:   eZLib/src/eZLib/Study/BouncingBall.java
	deleted:    eZLib/src/eZLib/Study/DiffSketch.java
	modified:   eZLib/src/eZLib/Study/VectorSketch.java
	modified:   eZLib/src/eZLib/Vector.java