UI improvement - keeping selected items selected

[frederikb96]

When selecting multiple pictures and using the share or move/copy button, the selection is gone after returning or executing the action.

From other apps, I know that the selected items are kept selected after an action is executed or if the action is aborted. This is especially helpful if one selected many items and accidentally used the wrong button, or if one accidentally copied and not moved the items and wants to delete the selected items afterward.

[scubajeff]

I would admit that the code of selection are really messy, especially for album related functions, there are quite a few ad-hoc patches. It will take sometime to fix this one.