Adding scaling, rotation and color blending for instances.

These properties are supported in the undo/redo commands. These properties are also now correctly interpreted when reading and writing gmx files.
In order to integrate these properties in Enigma, the following tasks need to be done in the LateralGm plugin : changing the instance's properties in the property : pre_creation_code. Also these properties must be supported when reading and writing egm files. As i consider the work to be finished in LateralGm i put already the commits in the repository.