ENH: add toplevel eval function

ENH: moar parsing

CLN: rename old Term to PyTablesTerm

get the original pytables file back

ENH: add arith and boolean ops to eval

more expressions work

ENH: remove dependency on passing locals()

DOC: add note about test type

ENH: add numpy and python engines
ENH/TST: py3 compat for division (no more operator.div) and error handling

CLN: default engine is now python
ENH/CLN: test engine results against each other

CLN: replace numpyengine with pythonengine

CLN: remove main
CLN: deal with scoping and add eval to top-level pandas
CLN: address the global/local issue by either letting numexpr handle or handle it in the same way as they do
TST: add test for global scope
CLN: rework the expression recursion