TST: sparse: add explicit zeros to matrices used in noncanonical format tests
TST: sparse: dense RHS/LHS are supported in comparisons for Numpy >= 1.8, so enable the tests
BUG: sparse: fix bugs in __eq__ with explicit zeros, and fix nan comparisons
[optimize] Bug fix of line_search_wolfe2: Optional arguments have not been passed to myfprime if the current value of the Jacobian gfk wasn't explicitly specified by the caller. This commit is to fix this bug
[optimize] Added missing returns in docstring of line_search_wolfe2. The function returns the new function value, the old function value and the slope at the new point, in addition to the value alpha and the number of function and gradient evaluations. But this info was missing from the docstring.
Merge pull request #3845 from trendelkampschroer/master

closes #3842
Merge pull request #3813 from pv/csr-comparison-fail

BUG: sparse: fix __eq__ for matrices with explicit zeros