BezierCubic2: Fixed intersect() not setting flag
Line2: Added swapEndPoints()
Gfx: Todo
Bbox2: Added expand()
GraphicGen: Now generates all logic gate types.  Also refactored.
ToolDragger: Fixed being cancel always being fired.  Fixes #7
GraphicComActive: Bubbles are now always drawn on top.
GraphicComActive: Now computes Bbox2 dynamically
EditorWorld: Comments
EditorStyle: Readability
EditorPanel: Added code to demo all logic gates.
Gfx: Improved grid drawing performance
ToolDragger: Drag threshold is now independent of camera zoom level
Fixes #4