Tabular pretty-printer for Algebra

[wisnesky]

Erik writes:
Related to #71.

The idea is to tabulate the Algebra from the Employees.aql example roughly as follows (but pretty):

Department (1) | secretary | name
----------------------------------
a.worksIn a a.worksIn.name


Employee (2) | manager | worksIn | age | first | last
--------------------------------------------------------
a a a.worksIn a.age a.first a.last
b b b.worksIn b.age b.first b.last


nat (2)
--------
a.age
b.age

string (5)
-----------
a.worksIn.name

Ryan comments:

The Show instance for Algebra is functional but rudimentary. This issue is to give it a nice tabular format.

Some day AQL-Haskell will emit e.g., HTML output but for now we just need something textual for interacting and especially debugging via the REPL / cmd line.

[epost]

I'm working on this with some guidance from Ryan.

[wisnesky]

This looks good to me, feel free to close the issue if you want.

[epost]

Thanks! :) I actually still want to implement your quote-stripping suggestions, as well as some other stuff, and I've been looking at a way to do some of it without going the Show route. But I'll do that under #71.