[RBFOpt] RBFOpt v2.0.0 available

[Giacomo Nannicini]

New features:

* More search options, including vastly improved default algorithms.
* Parallel version of the optimization engine, allowing asynchronous
parallel evaluation of the black-box function.
* Greater numerical stability.
* Improved command-line interface allowing easier execution on
user-defined problems.

This major version is not backward compatible, due to changes in the
interface to black box problems that were made necessary to handle
parallelization. Please see the file rbfopt_black_box_example.py to
see how to implement a black-box function compatible with v2 (such an
implementation should require very little effort on the part of the
user).

The software can be downloaded at: https://github.com/coin-or/rbfopt/releases