Seems that first/last button are still useful when there are a lot
of tabs. Using ctrl+click is not discoverable enough for the users
so for now bring the buttons back.
Also turn on enabling/disabling buttons when they have some
effect (this was turned off for Calc for unknown reasons).

Change-Id: I6bbb04d44066ebc6b89fe3d941ecafdbb378284a
(cherry picked from commit b6fe593c)
Reviewed-on: https://gerrit.libreoffice.org/19380Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Adolfo Jayme Barrientos <fitojb@ubuntu.com>
Tested-by: Adolfo Jayme Barrientos <fitojb@ubuntu.com>