Precis

Copperbox revision 1455.

I'm looking at Precis again, with the aim of turning the base code into a viable library for working with Cabal files.

Initially, I've added qualified imports for where code is imported from the Cabal / Distribution library. This was because I couldn't keep track of which were my own functions / types and which were Cabal's. Also a lot of the code is of very rough quality so I'll have to look at doing something about that.

Furthermore, some of the modules won't be generally useful, so I'll have to change the module name-space a bit to separate the general modules from Precis specific ones.