2 late fixes for 5.4
Review Request #124814 - Created Aug. 19, 2015 and submitted
do not call showOnScreenEdge for all clients when managing them or they change their geometry what will (aside the overehad) randomly show them on screen
update SwitcherItem::screenGeometry when showing not everytime the current screen changes.
a) that pollutes the geometry when the tabbox is invoked
b) it's insufficient for "Active Screen follows mouse" (the default)
c) less overhead (ok: "on multiscreen")
See tabbox bug
For the other patch: autohiding panel still basically works as expected (didn't conduct a vast test, though) and showOnScreenEdge doesn't get called for other clients anymore.