add features to TikzGenerator

• Add config to choose if all or only alive trajectories are drawn
• Draw walking direction in Tikz
• create nodes for pedestrian instead of circles. Each pedestrian node has a name 'ped_ID' to reference the node in tikz.
• add named coordinate at Centroid for all scenario elements:
  • source: (src_)
  • target: (trg_)
  • absorbingArea: (absorb_)
  • obstacle: (obs_)
  • stairs: (str_)
  • measurementArea: (mrmtA_)
• add style classes:
  • trajectory: i.e. thickness
  • pedestrian: default color
  • ped_circle: defines shape of circular pedestrians (not for groups)
  • selected: style for selected pedestrian
  • group: styl (all) groups.