Add Line of Sight (Visibility) system

[jonpas]

• Close Develop line of sight system #12
• Functions for setting tile visibility effect
  • Reorder layers correctly
• Add AETVObstacle class (opens Add Obstacles #86)
• Add SensorRange property to Ship
  • Set SensorRange to MoveRange + 1 (will take proper effect when 9d4fb56 is merged)
• Add tiled distance function
  • Restrict actions based on maximum distance they can be performed at
• Use Vector2D for Tile reference in Actions
• Make direct getters in GameModeBase in-line const
• Set board visibility based on ship ranges
  • Hook actions into changing visible tiles
  • Block clicking on not visible enemy ships
  • Hide enemy ships from ship list
    • Remove fill on ship list initialization (manually call in begin play after visibility is all set)
  • Allow firing (Laser and Torpedo) through fog
    • Apply damage without logging if ship hit
  • Add debug toggles for ignoring visibility and showing enemy visibility during its turn
  • Add UpdateVisibleTiles() function which updates the board effects if called from player side or debug is enabled, and additionally returns array of visible tile positions (if passed, pass by ref)
  • Add GetVisibleShips() function which filters all ships on board by visibility (pass by ref)
• Fix On(End/Begin)Perform() not being called in child classes
• Increase map size to 50x50
• Set all actions to end turn (at least for now - work on Project prototype finalization #83)
• Resize Base grid tile to have 1px border (instead of 2px)
• Change Hidden grid tile to black texture with 1px transparent border