Updated Allegro egg for Chicken 5, and other notes

Hi all,

It has been a long time since I've done anything related to Chicken, but as it would happen someone reached out to me with interest in using the Allegro egg with a Lisp game jam. To facilitate that I ended up having to go to some considerable lengths, because:

- The OpenGL egg doesn't seem to install on Windows.
- The OpenGL GLEW egg doesn't seem to be available for Chicken 5.

As it happens, Allegro provides its own GL extension management framework and so using an external extension manager is just additional bloat. So to solve the above issues I ended up providing both GLEW and GL wrappers within the Allegro egg, as the allegro-opengl module.

Which is to stay, the Allegro egg is now a free-standing library for creating indie games. There's no particular need for any other support eggs to get a game up and running.

I've updated the Egg to version 4.0.0; I'm not sure how Henrietta gets notified of this, because it's been so long.
https://github.com/dleslie/allegro-egg
https://github.com/dleslie/allegro-examples

As an side, it appears that the Apropos egg cannot be installed on Windows, either. In fact, attempting to install it irrecoverably breaks chicken-install, requiring a complete fresh reinstall of Chicken to get it working again. It appears that installing a dependency, check-errors, is the root of the issue. I've attached a screenshot of the offending error.

-Dan Leslie