schemas: Add settings to store keyboard numlock state

See merge request !25

schema: Add "locate-pointer"

See merge request !19

Initially, "locate pointer" was handled in gnome-settings-daemon using a
helper application which would work only on X11, not on Wayland.

While moving the feature to mutter/gnome-shell, however, the previous
setting in "org.gnome.settings-daemon.peripherals.mouse" is to be moved
to "org.gnome.desktop" instead.

However, having that setting in "org.gnome.desktop.peripherals.mouse" is
a bit too restrictive, because this is about the pointer and not just
the mouse (the device).

So add the new key "locate-pointer" in "org.gnome.desktop.interface" as
suggested by Carlos Garnacho.

!19
mutter!453
gnome-shell#981
gnome-settings-daemon!86

Overlay scrolling setting

See merge request !24

This setting will be used by GTK.

These settings shall be managed by mutter, so move them here from
gnome-settings-daemon.

schemas: Add "mount-removable-storage-devices-as-read-only" option

See merge request !23

Add lockdown option to prevent users from writing or modifying files
on removable storage devices. If enabled, gvfs is going to mount removable
storage devices (i.e. flashdisks, mobile phones, cameras) as read-only.

Remove old build systems

Closes #5

See merge request !20

(cherry picked from commit 2a59ca94)

Closes: #5