CLN/ENH: more reliable temporary variable mechanism
DOC: add doc examples for not and a more complex query
ENH: added interpretation of 'in' in pytables Term syntax

which is syntactically equivalent of '='
ENH: allow parsing of datetimes
ENH: give visitors their own term and const type class vars
TST: smoke test for datetimes
CLN/ENH: add syntax check before name resolution attempt
ENH: ensure that resolvers do not overlap with current scope