+ Added first tutorial level.
* Font now inserts line feed automatically if the next word is too long to fit.
* Gfx.c: added primitive list double buffering in order to gain some performance.
* MapEditor: now airport can be defined inside the tool.
* GameGui.c: new function GameGuiCalculateNextAircraftTime(), which calculates remaining time for next aircraft on the list.
* GameStructures.h: new parameter NextAircraftTime for TYPE_PLAYER structures.
* Game.c: added call to new function GameGuiCalculateNextAircraftTime().
* Game.c: GameRenderLevel() renamed to GameRenderTerrain().
* Game.c: GameRenderTerrainPrecalculations() has been created to perform some calculations which are stored in tables to be then looked up by GameRenderTerrain(). This should save us some calculation time during rendering process.
* Camera.c: added new CameraApplyCoordinatesToCartesianPos() prototype.
* GameGui.c: AircraftDataGPoly4 RGB data is now only calculated on startup.
* Game.c: new prototypes GameGetParkingDirection() and GameGetRunwayDirection().
* Slight optimizations into GameRenderLevel().
* Added some comment headers into Gfx.c.
* Aircraft.c: aircraft direction is now set according to runway direction when aircraft is created.
* Game.c: TILE_PARKING_2 was not included on AcceptedTiles[].
* Game.c: GameAssignRunwaytoAircraft() was not looking up runway exit/entry points correctly.