Commented out cached expression logic
testing with test_evalexpr
Use numpy equivalent of functions from math if possible.
Simplified complex_step, finite_step and is_complex_stepable
code for evaluating gradients of arrays works. Needs to be tested.
added test for broken assembly with boundary vartrees
Finished test for evaluate_gradient
Merge branch 'dev' of https://github.com/OpenMDAO/OpenMDAO-Framework into complex_step
Merge branch 'missing_deriv_fix' of https://github.com/JustinSGray/OpenMDAO-Framework into vtree_boundary
Merge pull request #1622 from Kenneth-T-Moore/bench

Metamodel fix for assemblies as models
Improved test coverage of derivatives code. Fixed _is_complex_stepable
Merge branch 'dev' of https://github.com/OpenMDAO/OpenMDAO-Framework into complex_step
removed visited check in _explode_vartrees from depgraph.
switched to sets of edges instead of nodes
need to check differently for visited
Found test_scaler_array_array_expression_issue
Fixed evaluate_gradient with ndarrays of integers.
fixes
Merge pull request #1625 from Kenneth-T-Moore/complex_step

Cal's Complex step story
numerical failure