Feature ai3

[till213]

• Minimise AI object creation/deletion requests when switching
  • User aircraft
  • Replay mode
• Prevent switching modules while recording (in order to properly store the flight vs single aircraft, depending on the current module)
• Properly stop recording (and persist the flight) when quitting the application (e.g. with CTRL + Q)
• Add git hash / date info to the About dialog, including 3rd party info
• Delete dialogs when closing (freeing up resources)
• Properly refresh the AI objects (in the simulator) when
  • Changing time offsets
  • User aircraft
  • Relative position
• Use HiDPI pixmaps based on actual device pixel ratio