Bbopt

Adds `unshuffled_sample` which is preferred to `sample` when shuffling order is not important.

Lots of changes; see README. Tagging now because I forgot to for previous releases.

Changed `bb.shuffle` to `bb.shuffled` to reflect the fact that it returns the shuffled list rather than modifying it in place unlike `random.shuffle`.

Add `partial_dependence`, `plot_partial_dependence_1D`, `plot_evaluations`, and `plot_objective`.

Adds `plot_convergence` and `plot_history`.