ObjFW  History of src/OFNotificationCenter.m of ed598fd8487309d3

These places are not super performance critical and the code becomes a
lot more readable.

Actually using @synchronized in ObjFW itself is also a good motivation
to optimize it further. file: [eb7640502b] check-in: [ff3a60cc12] user: js, branch: trunk, size: 7846 [annotate] [blame] [check-ins using] [diff]

This avoids retain cycles.

A future improvement could be to use a weak reference instead, without
relying on ARC by calling into the runtime functions directly. file: [bec84a1cd3] check-in: [5b5c12fa0b] user: js, branch: trunk, size: 8291 [annotate] [blame] [check-ins using] [diff]

This causes problems with Swift, which silently drops methods that use
types for which it doesn't have an interface. file: [7f71790adf] check-in: [651875bc1f] user: js, branch: trunk, size: 8322 [annotate] [blame] [check-ins using] [diff]

This prevents a deadlock when modifying observers from a handler. file: [7d4ea0e843] check-in: [93851ccd0f] user: js, branch: notifications, size: 5217 [annotate] [blame] [check-ins using] [diff]