Tweaked a bit plotting in OcpRt
Extended and cleaned the OCP class a bit:

- Ocp is the master class, as in the ACADO
- Mhe and Mpc classes are user interfaces...
Updated plotting functionality in the OcpRt class...

- Now it also plots yuNames and yxNames
- TODO horizon plotting of those guys should be further checked, but
  some initial tests show that it is just fine.