screen: Update for vte API

Corresponding to vte commit 371f90d40fa9b3331c3e10bab91bec4a63809a0b.
window: Implement read-only setting

Required vte commit 3868467b2d4613e5aa5f34c0d8e74abc3a38ef16.

https://bugzilla.gnome.org/show_bug.cgi?id=626747
profile: editor: Rename command tab

Since the title setting was removed, this tab only configures the command,
so rename it to "Command" only from "Title & Command".

https://bugzilla.gnome.org/show_bug.cgi?id=724110