[ENH] Adds a few arithmetical functions for rules
[ENH] Objects are selected by their name instead of index

This avoids mixing up selected objects on fov changes.
[ENH] The house is swinging
[REF] Code cleaning
[REF] "player" set as a variable
[ENH] Arguments for model and rules
[FIX] FOV init is now complete (with x,y,z,w not only image names)
[ENH] If an object has an action CLICK then it is fired without asking
[FIX] FOV is updated from the beginning, not after any first action
[ENH] Cat story example