Tease out independent components again.

[Chris Warburton]

This began as a collection of bash scripts (oh how times have changed!),
which were at least runnable as standalone commands.

The closest we have right now are the quickspecBench, hashspecBench and
mlspecBench commands, which are awful for the following reasons:

 - Their primary purpose is to benchmark these systems, rather than just
   run them.
 - They're FAR too complicated, mostly because of the benchmarking
   mentioned above.
 - They try to do too much, for example they include one mode which
   samples from TEB and one mode which takes TIP from stdin. They
   include TIP to Haskell package translation (from TEB). And so on.
 - Their functionality is reasonably modular, but it's invoked in weird
   ways (e.g. calling out to nix-build).

A lot of this is due to the requirements of benchmarking: we need to
repeat one bunch of work (the exploration) without repeating other
expensive work (like AST extraction); we need to be flexible enough to
support arbitrary packages, whilst ensuring the benchmarked sections
don't invoke any compilers; and so on.

Using asv lets us offload a bunch of these concerns:

 - Benchmarking and repetition are handled by our Python benchmark
   scripts.
 - Preparing the input (translation, etc.) can be taken care of by Nix
   and/or Python.
 - Compiling, setting up an appropriate environment, etc. can be taken
   care of by Nix, in benchmarks/default.nix.

We should try, as much as possible, to turn the actual exploration
systems into reasonably-standalone scripts. These should probably be
something like:

 - A TIP to haskell package script (taken from TEB)
 - A Haskell package to ASTs script
 - A TIP sample to ASTs script
 - A script to explore ASTs with QuickSpec (no reduction)
 - Ditto for HashSpec (no reduction)
 - Ditto for MLSpec (no reduction)

These should, as far as possible, avoid doing stuff like caching to the
Nix store. They don't need to, and they're modular enough that we can do
so in our benchmark environments.