The nxo_regsub class is a subclass of the nxo class.
As a side effect, set the thread's match cache, which can be queried via nxo_regex_submatch().
As a side effect, set the thread's match cache, which can be queried via nxo_regex_submatch().
This function combines nxo_regsub_new() and nxo_regsub_subst() in such a way that no Onyx regsub object is created, thus providing a more efficient way of doing a one-off subst.