Normally, when modifying user fields via JS, the "user modified" node.dab
flag would be set for that user (on all node's that user is logged-into) and
the user record automatically re-read (soon after). But this doesn't work
during newuser registration because the user is not yet "logged-into" a node.

This fixes the issue reported by Nelgin (and observed on amessyroom's BBS)
whereby if a new user resets/changes their external message editor, it would
not take effect for their new user validation email to the sysop (they would
still be using the default new user message editor as configured by the
sysop).

It's possible other new user default changes made (e.g. language) would also
not have taken immediate effect as a result of this bug (now fixed).