Add option to enable onscreen keyboard (linuxmint#59)

Add a switch to enable onscreen keyboard.

Move this new switch and the already existing layout selection list out
of section "Panel indicators" into a new section "On-screen keyboard".

usr/lib/lightdm-settings/lightdm-settings

@@ -254,14 +254,10 @@ class Application(Gtk.Application):
         row.set_tooltip_text(_("Choose which monitor should display the login window, or select 'Auto' if you want it to follow the mouse."))
         section.add_row(row)
 
-        section = page.add_section(_("Panel indicators"))
+        section = page.add_section(_("On-screen keyboard"))
 
-        row = SettingsRow(Gtk.Label(label=_("Hostname")), SettingsSwitch(keyfile, settings, "show-hostname"))
-        row.set_tooltip_text(_("Show the computer hostname in the panel."))
-        section.add_row(row)
-
-        row = SettingsRow(Gtk.Label(label=_("Accessibility options")), SettingsSwitch(keyfile, settings, "show-a11y"))
-        row.set_tooltip_text(_("Show accessibility options in the panel."))
+        row = SettingsRow(Gtk.Label(label=_("On-screen keyboard")), SettingsSwitch(keyfile, settings, "onscreen-keyboard"))
+        row.set_tooltip_text(_("Enable the on-screen keyboard."))
         section.add_row(row)
 
         onboard_layouts_path = "/usr/share/onboard/layouts"
@@ -276,6 +272,16 @@ class Application(Gtk.Application):
                 row = SettingsRow(Gtk.Label(label=_("On-screen keyboard layout")), SettingsCombo(keyfile, settings, "onscreen-keyboard-layout", layout_options, "string", size_group))
                 section.add_row(row)
 
+        section = page.add_section(_("Panel indicators"))
+
+        row = SettingsRow(Gtk.Label(label=_("Hostname")), SettingsSwitch(keyfile, settings, "show-hostname"))
+        row.set_tooltip_text(_("Show the computer hostname in the panel."))
+        section.add_row(row)
+
+        row = SettingsRow(Gtk.Label(label=_("Accessibility options")), SettingsSwitch(keyfile, settings, "show-a11y"))
+        row.set_tooltip_text(_("Show accessibility options in the panel."))
+        section.add_row(row)
+
         row = SettingsRow(Gtk.Label(label=_("Battery power")), SettingsSwitch(keyfile, settings, "show-power"))
         row.set_tooltip_text(_("On laptops, show the battery power in the panel."))
         section.add_row(row)