LinGui: add dialog to select multiple titles to add to queue

Replaces "Add All to Queue".
Dialog provides checkboxes to select titles to add to the queue and file
chooser/file entry to change destination file names.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6056 b64f7644-9d1e-0410-96f1-a4d463321fa5