before:
getFiles retrieves all files with their url
getSelectedFiles just returns getFiles result

after:
getSelectedFiles retrieves all files with their url
getFiles uses getSelectedFiles and truncates to 1 entry if necessary

See http://nabble.documentfoundation.org/Dev-f1639786.html for discussion

Conflicts:
	vcl/unx/kde4/KDE4FilePicker.cxx

Change-Id: I56a0e2bc877f93e28f08d5ebaafd1826a92cef8b
Reviewed-on: https://gerrit.libreoffice.org/17025Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>