Re: Remove the complicated nix-support/*specBench stuff

[Chris Warburton]

Removed most of the cruft associated with quickspecBench. We should now
rename it to quickspec.nix and re-organise it to simplify the remaining
functionality.

In particular, we should have:

 - tipToHsPkg - a converter around full_haskell_package; should use
   inNixedDir to cache the result to Nix, and should generate a
   default.nix file in there too
 - hsPkgToAsts - takes a Haskell package dir and outputs annotated ASTs.
   Should generate a default.nix if there isn't already one, and should
   tincify to ensure we satisfy all dependencies. This should output to
   stdout, so that we can use pipeToNix at our own discretion.
 - quickspecAsts should accept a haskell package dir as argument and
   ASTs on stdin, explore the package and spit out an array of equations
 - quickspec should take a haskell package dir as argument, explore the
   package and spit out an array of equations