Start OOPing up the schedule generator.

The idea here being that we can, in code, switch between what kind of
formula we're generating.
Move some preamble stuff to oop code.
Move Some Things to Z3/not specific code paths
Allow identifying a slot round variable.
Parameterise (ish) the output fetching too.
Use an internal project method
Fix model fetching gunge.
Write a QF_BV model writer.
Split syntax-specific code out into sep. files
Update .gitignore
Start a script for reading model outputs
Move some utilities to a utility file.
Attempt to bake a small lisp parser.
Expressions can also just be raw symbols.
Attempt to add bitvectors to our expr.
pyparsing wants expr def in one line...
Pyparsing doesn't want explicit newlines
Get pyparser to read stdin
Start looking at the input parse tree.
Speculate how I want parse interpretation to work.