Add custom color and shape to the inspector graph

[Nyan11]

It could be usefull to add a color and a shape to the component who are BlElement.

To do it, we could add a pragma with a rule to detect the component that are BlElement and change their colors and their shape.

It would be nice to also generate a legend to the roassal graph with the different colors and shapes + the logo for event/services/parameters.