Moved the compressed versions of the material, evolve, sourceprops,
photonstatistics and output modules to a separate directory, called compressed.

The modules use a compressed version of the ionized/neutral fractions
but have not been kept up to date. They are to retained for future
use but are for now moved out of the way to create a cleaner source
directory.
A README file explaining the compressed ionized/neutral fraction idea.
Merge branch 'master' of github.com:garrelt/C2-Ray3Dm