Added a context menu "Edit Presentation" when in Autplay mode.
This has been discussed and approved by the Design team: https://wiki.documentfoundation.org/Design/Meetings/2013-07-20

Change-Id: Ic229e54bd10d23f999f1d746cce38c4004504d28
Reviewed-on: https://gerrit.libreoffice.org/4960Reviewed-by: Luboš Luňák <l.lunak@suse.cz>
Tested-by: Luboš Luňák <l.lunak@suse.cz>