Make sure that the Simulation / Phase plane is 100% correct with all its equations and everything

This task includes the following issues to be resolved:

• get the correct equations from somewhere and using and maybe learning a little bit more of matjax make sure that all of them are displayed correctly both in the help tag and outside of it
• -find out what is the usage of _numpy_dfun (where it is called, can't we just copy all formulas in dfun)
• talk with Lia if the way I handled the changes in dynamic_model_controller is acceptable and can be merged
• check for other issues on this page (that page looks different for every model)