MaintenanceDispacher, tests and inspection of people

This merge request combines several smaller features and improvements:

• adding MaintenanceDispacher (#29 (closed) and possibly #8 (closed))
• adding tests for Visitors (#37 (closed))
• implementing inspection of all people (#31 (closed))
• adding ability to display bool type as "<Name>" or "Not <name>"
• smaller bug fixes and improvements
  • dividing by zero when a buiding is free to enter
  • idle staff
  • using static Simulation.Random everywhere