Airstrike on glSDL

[Ulf Ekström]

Hi All. The game is progressing at its usual slow speed, but we are
getting there. As Eero had observed some slowness when he put a lot of
sprites in the same level, and 95% of the time was spend blitting, I
tried to link Airstrike to glSDL, the SDL OpenGL backend. The game
runs _very_ fast with this library, even on my sucky graphics card and
the DRI opensource linux drivers. Also the delay function is not
working with glSDL, so I get 10x game speed as well. Anyway we should
definitely make a glSDL binary when the next release of Airtrike is
done, as far as I know Linux and Windows are supported by glSDL.

Game TODO:

Before release:
Menu system [Ulf]
Biplane AI [Ulf, anyone else?]
Game logic [Eero/Ulf/Everyone]
More biplane models (the damaged plane model is lost..) [Anyone?]
Persistent configuration [Ulf]
Make the game fun [Everyone!]
Levels, polish.
Weapons 
..

Ulf