REFACTORING: FleetManager class added and following functionality moved there:

- Roomba-related functionality has been moved from mainwindow
- POI and wall -related functionality has been moved from mapQGraphicsView
- passing tracing related commands has been moved from mapQGraphicsView

other notes:
- Adding/Removing from scene is now distributed (used to be done through
  mapQGraphicsView)
- individual selecting of roombas and start points need to be
  implemented for complete multiple roomba support
- clever removing of start points not reimplemented yet
- needs testing with roomba
REFACTORING: Multiple Roomba support ready (untested)

- All essential refactoring done IMO, but needs testing
- added roomba-selection logic to sensorUpdateTimerTimeout()
  (not sure how well it works)
- moved adding traces to scene away from mapQGraphicsView to
  IRoomba (it now has pointer to map)
- added isReady-function and variable to iRoomba. Roomba is now
  ready in safe and full modes.
- startPoints are still unmovable
REFACTORING: added comments and improved checkPoiCollision()

- some short explanations added where propably needed
- checkPoiCollision() should now exclude traces (needs testing)
REFACTORING: timer logic updated

- roomba instances now handle autocapture completely within and update
  their state. FleetManager has a separate timer for reading the states.
  Intervals of the timers should be same to avoid loss of data.