Update perftest to run single files
Add scripts to generate the lr tables

This allows the parser to used the cached lr table for a significant
performance boost.

Due to the way that ply caches/verifies the generated lr table, we
need different versions for both py3 and py2.

What this means in practice is that you'll have to run
bin/gen-tables on both python2 and python3 when changing the grammar.
Add note in README about how to regen the lrtables
Merge branch 'gen-lr-tables' into develop

* gen-lr-tables:
  Add note in README about how to regen the lrtables
  Add scripts to generate the lr tables
  Update perftest to run single files
Regen lrtables