Flocking, Main, Food, Colors

The flocking behaviours were completely rewritten to be better
balanced, and to actually calculate things correctly. Still need to
abstract their parameters out to be tweakable.

Fixed graphics drawing, improved OpenGL perf slightly on my custom line
function, fixed background drawing over things, and added double buffer
to the antialiased version. Should be stable enought to use
antialiasing all the time now.

Started work on Food. Added skeleton of the class, with basic physics
and a nice fall then slow down in water effect. Gravity is set on the
world.

Also added slight variations to the fish colours. And created a new
colour-scheme file to visually keep track of the colours I'm using