Reset the animation of the model marks when the loop is not full.

The animation associated with the marks of the models were not restarted when
with the action if they looped infinitely. Thus, if the animation had a part
before the loops, it was not seen.

The new behavior seems better:
- fully infinite animations play smoothly when they are shared among several
  actions,
- the first part of the other infinite animations is visible when the action
  starts.