Make GSettings support optional, refactor text entry handling,
fix some off-by-one bugs in the management itself, use Params
for parsing, fix other typos and bugs.
https://bugzilla.gnome.org/show_bug.cgi?id=642793
runDialog and lookingGlass both implement a home-made history
manager, each working slightly differently than each other in
behavior and implementation.
Extract the behavior and implementation from runDialog, which
reads and saves to GSettings.
https://bugzilla.gnome.org/show_bug.cgi?id=642237
