Event versioning

[dzervas]

Event versioning should be added so that changing a single call arg does not break all the hooks

[dzervas]

Example usage:

from hooker import EVENTS, hook
EVENTS.append("ahook")

@hook("ahook", version="0.1")
def a():
    return "a"

@hook("ahook", version="0.2")
def b():
    return "b"

EVENTS["ahook"]["0.1"]()
EVENTS["ahook"]["0.2"]()
EVENTS["ahook"]()  # What happens here?

What should EVENTS["ahook"]() do? should it call the "latest" version? If yes how can I order a version? what if the "version" is blabla and caca? Alphabetical order?