emulation: Make OSC response use the same terminator as the query

https://bugzilla.gnome.org/show_bug.cgi?id=722446
widget: Maintain selection when rewrapping

https://bugzilla.gnome.org/show_bug.cgi?id=722635
widget: Maintain selection when rewrapping, take 2

https://bugzilla.gnome.org/show_bug.cgi?id=722635#c7
widget: Fix selection's padding adjustment

https://bugzilla.gnome.org/show_bug.cgi?id=722873