Add length to Vect
Support :apropos in IDESlave
Make :apropos case-insensitive
Improve display of :apropos

 * Don't show elaboration artifacts (ie only display UN and NS of UN)
 * Sort the names
 * Show full namespaces
Add some docstrings
More docstrings
Addition and multiplication of Fin

Useful for indexing into Vects of Vects
Add highlighting for keywords in interpreter output

Fixes #929
Merge pull request #977 from jedesah/vect_length

Add length to Vect
Merge pull request #979 from david-christiansen/feature/apropos

:apropos improvements
Merge pull request #981 from david-christiansen/docs

Add some docstrings
Merge pull request #984 from david-christiansen/fin-add-mul

Addition and multiplication of Fin
Merge pull request #985 from david-christiansen/keyword-highlight

Add highlighting for keywords in interpreter output
Add a note to Vect.length about when to use it

Also add some other docs while I'm at it
Support text formatting in docstrings

Now, Markdown text formatting is no-longer a no-op. Needed to make the
stern warning on Vect.length look reasonable.
Remove java tests from travis

They are currently getting in the way... we need some way of separating
the backends since we clearly can't reliably support every one that
anyone might want to add.
Merge pull request #980 from david-christiansen/jedesah-vect_length

Add some vector docs
Add basic elaboration context tracking to unification
Actually track applications in the elaborator wrt unification fails
Track the providence of unification errors

Unification errors can now be wrapped in a constructor specifying what
function was being applied when they were generated, where it was in the
source, and which argument of the function had a problem.