[GUI] Revise VADERE settings dialog (cog icon in online/post visualization)

Two things should be changed in VADERE's settings dialog (see screenshot below):

1. At the coloring options for pedestrians (see red box below), only one option can be chosen at a time (and not the four options). Currently, the last selected option wins. In the long run, only three options are necessary:
   • Color pedestrians by using logical expression (see LogicalParser). Include grammar examples directly.
   • Random colors
   • By evacuation time
   • Note: Maybe, this should be designed by using radio buttons. I.e., not selected options are greyed out.
2. Option "By evacuation time" requires the corresponding output processor. Therefore, a warning text should be placed in settings dialog.