graphics bugfix

graphics:
-fixed error in drawing scaled rotated images causing them to be drawn
at half-size

Aircraft:
-reduced scale factor of planes to account for fixing of the above bug
Clouds.

Now. With. Clouds.
Took me far too long to work out why they were being drawn at half the
size they should and looking rubbish... see the previous commit.

TransferBar:
-Allows planes to be submitted, take some time to travel, and then be
available for pulling from the other end
-Meanwhile, draws pretty pictures.
+Clouds. Lots of clouds.
!clouds should be resized to any power of two to enable proper scaling;
OpenGL fills the blanks
!Logic for transfering planes is untested; attempts to lever existing
pathfinding logic.

Multiplayer:
-now includes a TransferBar instance.
+receives updates, but not have planes fed in/out at the moment

Title:
!replaced exit button functionality with a link to a Multiplayer scene
+temporarily, to enable visual inspection without the other
infrastructure