Full DiffEq Compatibility and Improved Performance

There were some performance improvements, the tests are greatly expanded, and full diffeq compatibility. In order to get diffeq compatibility, a dependency on DiffEqBase.jl was needed, but that's lightweight enough (and the compatibility code is really small, just diffeq.jl, and only pertains to size changing and nothing else) that it doesn't deserve a separate package. I think I will take the same approach with whatever NLSolverBase comes up for full compatibility with NLSolve/Optim if necessary. Oh an ForwardDiff.jl works on these now, so that will probably solve the last of the "linking" problems.