[Pharo-project] PinMorph and GeeMail* cleanup

Hi, I invoked the pointer finder in 10070 and found a few things. Code changes are in the attached changeset. Manual cleanup: CustomEventsRegistry at: #scrolledIntoView put: IdentityDictionary new. CustomEventsRegistry at: #scrolledOutOfView put: IdentityDictionary new. There is still a reference to GeeMailMorph in the Flaps. I'm not sure what would be an easy way to remove to reference. Maybe a manual action would be sufficient But I don't know how to remove it that way, too :)) Norbert