- reduced friction on normal and breaking ground so that the car takes a bit longer to come to a complete stop after releasing the accelerator
- means the length of the slow down sound matches better
- Level Editor (continued...)
    - added a tile cursor which is positioned over the tile where the mouse is pointing
- Level Editor (continued...)
    - now holding left mouse down while mouse moving continues to delete moused over tiles
    - increased scroll speed by a factor of 4
- changed TiledMapBuilder.addTileToLayer() function
    - now does nothing if adding the tile would mean no change to the layer
    - now removes existing tile (if exists) before adding tile

- changed TiledMapBuilder.removeTileFromLayer() function
   - now does nothing if there is no tile to remove on the layer for the given row and col
- Level Editor (continued...)
    - can now add 'GROUND', 'MUD', 'ICE', 'BREAKING', 'SOLID'
    - use number keys 1 - 5 to select block to add
    - tile cursor's z position is now adjusted depending on whether we're in delete mode, add ground tile mode or add solid tile mode
- Level Editor (continued...)
    - refactor to reuse z position calculation
    - each edit mode is now aware of its tileName and tileLayer
    - addTile() now simplified to take editMode instead of tileName and tileLayer
    - simplified performEditOperation() and TileCursor component
- Level Editor (continued...)
    - added outline to tile cursor so that it can be seen when the its tile is the same as the current map tile its positioned over
- Level Editor (continued...)
    - holding the shift key now draws a grid covering the area from the current tile cursor position to the latest added tile
    - this grid indicates the area that will be filled if the left mouse button is clicked (Note: implementing the actual fill functionality next)
- Level Editor (continued...)
    - implemented fill functionality: after placing a tile, hold the shift key to mark an area to fill while moving the mouse, then click the left mouse button to fill the marked area
- Level Editor (continued...)
    - implemented delete area functionality: after deleting a tile, hold the shift key to mark an area to delete on the same layer by moving the mouse, then click the left mouse button to delete the marked area