MBS-5734: allow a hash argument to _expand and MB.i18n.expand, to specify target _blank, classes, etc.
Merge branch 'mbs-5734-i18n-substitution-hash' into beta

* mbs-5734-i18n-substitution-hash:
  MBS-5734: allow a hash argument to _expand and MB.i18n.expand, to specify target _blank, classes, etc.