Create Mediator for fading views based on the value
Add methods to easily work with Property as a number
Fix Math rounding to accept zero scale
Fix Invocation's detection of deallocated target

If the invocation's target is subtitued, it no longer considers nil target as a reason to give up and release the invocation.
Fix fixed Invocation's detection of deallocated target

That fix was wrong, since target always has placeholder :( Now I use flag to know whether the target is consumed or stored.
Fix Timer precision so it rounds produced values
Add Timer.elapsedTime property and shorhand producer