Repeating canvas fields

[Gulix]

See also #17

Some elements are repeating themselve in the canvasFields array. For example, a Path for a specific box repeated multiple times in the canvas, with only x & y coordinates changing. It will be good idea to have a way to repeat those elements without repeating all the code (gain in space, maintainability, evolution, ...)

[Gulix]

Maybe a way to add variables to Globals ? #162