This fixes a lot of unnecessary exports in the specs, removes a couple
otiose imports (comonads and semigroups are provided by base, I beleive),
and removes a duplicated function.
This interface has already been obsoleted—its only consumer has a
private interface for its caching functionality, and @robrix's work
will restore a generalized version. No reason to keep this about.
During my recent pairing with @robrix, we agreed that the name of
Linker was inaccurate—it doesn't link anything, it just keeps track of
past modules. This renames it and its module.
The caching analysis had been disabled, as it was still written in the
open-interpreter style. This patch restores it, defining a
`CachingAnalysis` newtype that uses nondeterministic but convergent
caching in its `MonadAnalysis` instance. This also defines an
`embedSubterm` helper that is useful in defining new analysis passes.
Thanks to @robrix for 🍐!
