Cabalize

Package versions are mostly as produced by cabal init on my
system (that is, more or less what I happened to have
installed).

Feel free to enlarge the dependency range for what you have
installed, as long as the code still works.
Document how to run demo

I needed to check the source to find the right URL, so I
documented it.
Declare the status as "early prototype" in README.md

Since the demo is still not ready for wide exposure, I added a
warning that this is still an early prototype. This will avoid
disappointing casual users who will go to the homepage and read
the README.md.
Add .gitignore
Move source files into directories.

This is necessary to setup compilation of the examples without
recompiling the library each time.
Cabalize.
Remove unused dependencies.
fixed merge, in favour of Toxaris cabal file