Simplify suggested `git push' command.
Add initial setup.py.
Fix stack management on empty reductions.

del yystack[-n:] is supposed to remove n elements from the end of
yystack, but if n is zero, it empties the whole stack instead!
Fix parsing of %fallback directive.
Call p_foo_x, not x, for rule `foo(x) ::= ...'.
Use an array of actions, rather than getattr of action_%03d.

Yields a ~5% speedup.
Don't put lemonade output files in the working directory.
Generate bayeslite/grammar.py automatically in setup.py.

Mechanism is a mega-kludge because distutils and setuptools are
brain-damaged.
Omit debugging print.
Clean first in check.sh.
Pass a nonempty PYTHONPATH through in check.sh.