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
TST: add failing modulus tests
CLN: use format string for unicode
CLN: remove engine detection and manip for datetimes
ENH: add Term and Constant