Adds license CeCILL-B
coq: setup-hook for libraries

Adds a hook to automatically populate the $COQPATH variable.
Coq libraries are expected to be installed in

    lib/coq/${coq-version}/user-contrib/
Adds three coq libraries: containers, mathcomp, ssreflect

Containers is a reimplementation of the FSets/FMaps library from the
standard library, using typeclasses.

Homepage: http://coq.inria.fr/pylons/pylons/contribs/view/Containers/v8.4

The Mathematical Components (mathcomp) contains advanced theory files
covering a wide spectrum of mathematics.

Homepage: http://ssr.msr-inria.inria.fr/

Ssreflect is a proof language (plugin for Coq) and a small set of core
theory libraries about boolean, natural numbers, sequences, decidable
equality and finite types.

Homepage: http://ssr.msr-inria.inria.fr/
Removes duplicate ssreflect
ProofGeneral: makes the dependency on TeXLive optional

And fixes the default value of $PGHOME
nixpkgs manual: packaging coq libraries
Merge pull request #4305 from vbgl/coq-containers

Working with Coq