Precis

Copperbox revision 1457.

I've made a major re-organization of the directory structure, so that the modules that will hopefully soon be generally useful (i.e. the ones that work with Cabal files) are distinguished.

I've also started changing a lot of the types that were previously aliases to concrete but opaque types. As a number of these types represented file paths or fragments of file paths, I want to keep track of them more effectively e.g. whether or not the path is separated, normalized...