Relaxed Signals

[creynders]

I encountered a situation in which I needed to be able to add a listener to a signal after it having been dispatched already. In other words, let the listening object be indifferent to whether the signal already was dispatched or not.

[removed rest of comment due to being irrelevant after latest commits]

[creynders]

I created relaxed signals extending all the corresponding original signals and put them in a subpackage "relaxed".
I tried going the decorator road, which would've been cleaner, but became unnecessary complex due to the inheritance chain of the classes and interfaces of the originals.
I also added tests for all of them, but I must confess I'm no test meister, so it could be they're incomplete/useless/idiotic ...