Optim v1.0.0

Significant changes to the Non-, Once-, and TwiceDifferentiable setup; these now hold temporaries relevant to the evaluation of objectives, gradients, and Hessians. They also hold f-, g-, and h_calls counters
Refactor tests
Drop v0.4 support
Add limits to f-, g-, and h_calls

Optim v0.7.6 release notes

Various bug fixes
Deprecate DifferentiableFunction, TwiceDifferentiable in favor of OnceDifferentiable, TwiceDifferentiable
widen some type annotations (e.g. allow for multidimensional arrays as inputs again)
introduce allow_f_increases keyword in Optim.Options to allow objective to increase between iterations
New option in Optim.Options: allow_f_increases. Defaults to false, but if set to true, the solver will not stop even if a step leads to an increase in the objective.
Newton and BFGS: set initial step length to one. See 328.

OptimizationOptions is now unexported, and has been renamed to Options. Must be accessed as Optim.Options as a result.
Bug fixes to Nelder-Mead tracing.
Keywords with ! in them have been deprecated to version without. For example, linesearch! -> linesearch.
Failures in a line search now terminates the optimization with a warning and status of non-convergence. The results can still be accessed, but minimizer(res) will not represent a local minimum. See 275.

Refactor code internally to clean up code and allow more flexible use Optim
Switch to new (v.0.3) ForwardDiff
Make minimizer/minimum transition final
Fix dispatch bug for univariate optimization.
The line search functionality has been separated into a new package LineSearches.jl, see 277.
Make move to minimizer (the argmin) and minimum (objective at argmin) final: field names are now in sync with function based API.

Assess convergence in g before iterating to avoid line search errors if initial_x is a stationary point
Fix trace bug in LevenbergMarquardt.
Add ForwardDiff AD functionality to NewtonTrustRegion
Make documentation even more noticable in README.md