ENH: add new computation module and toplevel eval function
ENH/TST: add new instance testing functions and their tests
BUG: prevent certain index types from joining with DatetimeIndex
TST/ENH: add 2d bare numpy array and nan support
ENH: add modulus support
CLN: use format string for unicode
CLN: remove engine detection and manip for datetimes
CLN/ENH: encapsulate Terms and Constants
ENH: allow an already-parsed expression to be passed to eval
CLN: add automatic scope creating object
CLN: make the environment an implementation detail
DOC: add docstring to eval
CLN: have the Scope instance auto create the scope if none exists
CLN: add six.string_types checking instead of basestring
CLN: use shiny new string mixin to refactor repring
CLN: move align to its own file
CLN: use new stringmixin for Expr base class
ENH/CLN: be more careful about unicode
DOC: reference future enhancingperf.eval section
API: expose the computation.expr.Expr object to top level pandas