Resized the airspace 32 units down from the top. This made the mouse
event off by 32 units, which I "fixed" by adjusting the mouseY position
when you enter the demo screen. There's a new variable for this in input
which gets set to 32 when you enter the demo and 0 when you exit.
Readjusted the entry and exit points and their name labels.

Changed the colour of entry/exit points to yellow.

The compass still needs adjusting as does the disabling of manual flight
mode when you fly out of the airspace at the bottom.
Preliminary version of the resized airspace. Hover over to show flight
plan is still wrong but I've left it as I think Liam M has done
something on it.
Merge gui_update