Added GraphicPanel class
Added Clipboard class
EditorWorld: Added support for selection/clipboard operations
EditorCreator: Linked cut/copy/paste actions
Clipboard: Added comments and clear()
EditorWorld: Fixed performance issues when deleting lots of components
Clipboard: Fixed reference to wrong selection
EditorController: Removed debug printlns
Selection: No longer responsible for cut/copy/paste/delete actions
ToolContextual: Now handles cut/copy/paste
ToolManager: Cut/copy/paste support
Simulation: Added toString()