added inheritance doc

doc/inheritance.txt

@@ -0,0 +1,69 @@
+Object Hierarchy for jsPlumb
+----------------------------
+
+
+EventGenerator - jsPlumbUIComponent - OverlayCapableUIComponent - Connection
+			   |					|							|
+			   |					|							- Endpoint
+			   |					|		
+			   |					|
+			   |					|
+			   |					- DOMElementComponent - DOMElementEndpoint - Endpoints.Image*
+			   |										  |					   |
+			   |										  |					   - Endpoints.Blank
+			   | 										  |
+			   |										  - AbstractDOMOverlay* - Overlays.Custom - Overlays.Label
+			   |
+			   |
+			   - jsPlumbInstance
+			   |
+			   - ContinuousAnchor
+			   |
+			   - Anchor - FloatingAnchor
+			   			| 
+			   			- DynamicAnchor			   
+
+
+
+Segments.AbstractSegment - Segments.Straight	
+						 |
+						 - Segments.Arc 	
+						 |
+						 - Segments.Bezier
+
+
+
+AbstractComponent - Connectors.AbstractConnector - Connectors.Bezier
+				  |							 	 |
+				  |							     - Connectors.Straight
+				  |								 |
+				  |								 - Connectors.Flowchart
+				  |								 |
+				  |								 - Connectors.StateMachine
+				  |	
+				  - Endpoints.AbstractEndpoint - Endpoints.Dot
+						   					   |
+						   					   - Endpoints.Rectangle		
+						   					   |
+						   					   - Endpoints.Blank
+						   					   |
+						   					   - Endpoints.Image*
+						   					   |
+						   					   - (Endpoints.Triangle)		
+
+
+Overlays.AbstractOverlay - Overlays.Arrow - Overlays.PlainArrow
+						 |				  |
+						 |				  - Overlays.Diamond
+						 |
+						 - AbstractDOMOverlay*
+
+
+
+Objects with Multiple Inheritance:						 
+----------------------------------
+
+* ImageEndpoint extends from both Endpoints.AbstractEndpoint and DOMElementEndpoint
+* AbstractDOMOverlay extends from both Overlays.AbstractOverlay and DOMElementComponent
+
+