Move Ivoker to consumers
Merge branch 'master' of https://github.com/iMartinKiss/Objective-Chain

# By Martin Kiss (10) and Juraj Homola (3)
* 'master' of https://github.com/iMartinKiss/Objective-Chain:
  Fix Transformer.formatString: crash, improve formatting different counts
  Fix Property declaring correct produced value class
  OCAFilter: Add produceNotNil filer
  OCATransformer+Collections: Fix misused "keys" and "key" variable in keyedArray: method.
  Fix detection of common value class from array
  Fix Math collection operators
  Disable class detection in OCAHub.
  Improve Timer constructor names
  Fix Transformer.formatString: when replacing NSNull
  Key-Path Accessor replaces NSObject class by nil
  Notificator sends initial fake notification
  Fix Notificator convenience derivation methods declaring wrong value class
  Add Math.randomUpTO: transformer
New Variadic macros for arrays + tests
Move Hub chaining method to Producer
Comments for Producer including subclassing notes
Comments for Command
Style improvements for comments of Timer, Command and Producer
Implement dependency Hub + tests
Modernize Bridge interface and chaining methods to use variadic arguments
Add new Context constructors and comments, modernize chaining methods
Add comments for Mediator class
Modernize Filter chaining, add new constructors + tests
Fix Timer not accepting zero interval
Implemente Throttle Mediator, that limits frequent values
Rename Throttle delay to interval, add comments
Documentation for Consumer, new -chainTo: method
Modernize Subscriber API, add comments
Implement Invocation argument substitutions using placeholder objects
Refactor Invoker to treat target as regular placeholder