client: legacy: Reimplement deprecated --title option

This reverts commit 0033eca2.

Reimplement the deprecated --title client option. It seems it is absolutely
required by all those super l33t unix admins that are above using a lowly
command like printf(1) or the even simpler xtermcontrol(1).

https://bugzilla.gnome.org/show_bug.cgi?id=740188