Had my breakthrough of how to handle all features of opengl textures
while still making it beautiful.
I'm currently doing the work implementing the basic objects so that
I can start unifying the gl-array and texture-array worlds.

Also, as I am using immutable texture storage (for now), I have added
a function that runs when cepl:repl has got a gl-context. The function
checks to make sure that the required extensions are available.
{WIP} THis should really be in a branch but no-one watch this yet (right?) so I will just keep going.
Made more progress on textures