Title being ignored on update when optional.

Ran across an issue where a node was set up with Auto Entity Label in mode 2 (Automatically generate the label if the label field is left empty).
When editing the node title, upon submission the title would reset to the Auto Entity Label pattern.
Turns out that part of the logic is checking for a {auto_entitylabel_applied} parameter on the entity which is only set when the title is updated, and then on each edit it is not persisted.

I am going to submit a patch which will hopefully tidy up some of the logic and make it more readable at the same time.