Adds a new way to resize an element in the COmpositionArea. So there is to way :
- By resizing with the mouse : resize directly the GraphicalElement. Fast and usefull when the GE ratation angle is 0°. But useless when the angle is diferent from 0.
- By holding the AltGr key and resizing with the mouse : resize the representation (the CompositionJPanel) corresponding to the GE. The CompositionJPanel will takes the new dimension and the GraphicalElement will be adapt to fit inside the rectangle. But still some minor bug to fix (Sometimes 1 pixels too widie or too short)