shelve: move 'nothing changed' messaging to a separate function This has nothing to do with the future obsshelve implementation, I just thought that moving this messaging to a separate function will improve shelve code readability.

shelve: move commitfunc creation to a separate function Special commitfuncs are created as closures at least twice in shelve's code and one time special commitfunc is used within another closure. They all serve very specific purposes like temporarily tweak some configuration or enable editor, etc. This is not immediately important to someone reading shelve code, so I think moving this logic to a separate function is a good idea.