Add getter/setter properties in the Sinus primitive allowing to change sinus behaviour while the mouvement is running.
This avoid having to stop and override a sinus primitive when you just want to change the amplitude or the frequency.

/!\ a specific property in the Cosinus primitive for get/set the phase has to be done before merging in master.
Merge pull request #11 from matthieu-lapeyre/sinus_primitive

Add getter/setter to the Sinus primitive
Bugfix: Some variables name were the same as the getter/setter methods name.
bug fix in move.py: calls to LoopPrimitive update method no longer needed.