entryArea: Share a single NickPopover
As outlined in the previous commit, there is no real need for keeping hidden popovers for every room around all the time. Just share a single popover between all entryAreas to cut down on the number of widgets (and the resulting overhead of GTK+ updating their state etc.).
wip/fmuellner/singleton-nick-popover in 3 minutes and 25 seconds (queued for 2 seconds)1 job for