It inserted the new items one position after the given one and inserted all new items
at the same position resulting in the items being in the reverse order of the
input array.
It was decided to make these behavioural changes because this function has according to
https://codesearch.debian.net/search?q=g_list_store_splice only one real user (nautilus)
and it didn't do what one would expect from reading the documentation.
https://bugzilla.gnome.org/show_bug.cgi?id=795307
GListModel is an interface that represents a dynamic list of GObjects.
Also add GListStore, a simple implementation of GListModel that stores
all objects in memory, using a GSequence.
https://bugzilla.gnome.org/show_bug.cgi?id=729351