v2.2.1

Optim v2.2.1

Diff since v2.2.0

Merged pull requests:

• Guard against gbarrier_norm == 0 in computation of initial mu (fixes #1233) (#1257) (@RafaelArutjunjan)

Closed issues:

• Default value of Fminbox.mu0 = NaN causing optimisation failures on v2.0.1. (#1233)