Create a slideshow from a series of image files.
Created the dialog window (called photoalbum.ui).
Image preview is working.
Options "Fit to slide" and "1 image and title" are implemented.
Added a title page with the author's full name.
TODO: 2 images / 4 images per slide
      i18n of messages
      UI tweaks

Change-Id: I14b337187dc5d373fcd28489098fda813b5fd5f6
Reviewed-on: https://gerrit.libreoffice.org/2582Reviewed-by: Andras Timar <atimar@suse.com>
Tested-by: Andras Timar <atimar@suse.com>