Add user guide showcasing all functionalities of JuPedSim

[schroedtert]

Add a user guide like the one for PedPy, which showcases all functionalities of JuPedSim. This would allow users to have a point to start to look for inspiration what they could achieve with JuPedSim.

From a user, who started using JuPedSim with the help of the website:

• In general: I miss the user guide like in Pedpy... You can scroll through it and possibly find ideas for things you've never heard of before, but which can improve/simplify your own calculations. With Jupedsim you have to know what you are looking for to find it. Sometimes (or very often for me as an absolute Jupedsim newbie) you don't know exactly what you are looking for, but are still very open to the many different possibilities. And with the current documentation, you are still relatively often lost in the API.