Added airplane and other improvements

Added airplane (control with the mouse, left click to shoot, right-click to drop the bomb)

Added build zone to prevent building outside the map.

Solved a bug which caused the camera to look down on some creations.

Solve a bug which caused the missile or cannon to crash if the creation was empty.

Made it possible to fly faster by using the Ctrl key.

Removed the block placing highlighter from the picture when saving a creation.

Solved a bug that prevents flying forward/backward while the camera was pointed straight down.

Improved the sky (no more hemispheric sky).

Got a new server in New Jersey & domain https://buildncrush.com/