Maintain and update disp_nick column.
Maintain and update disp_nick column.

Reduce the number of places a user row can be created down to one
subroutine, and make sure that subroutine populates the disp_nick row.

Continuing work on issue #1.

jfautley/pah-irc,grifferz/pah-irc,jshholland/pah-irc