Don't make config key change and size change conflict
Use a single timer instead of two and use flags for events that can lead to a relayout. the flags at the moment are size change and config key for serialization change.
if they happen in the same moment (for instance when the serialization config key is dependent from the size) if the new key already is saved consider it correct and don't try to keep the distance to screen edges from the old layout, ruining the saved one
to be used in conjunction with plasma-desktop!385 (merged)
Edited by Marco Martin