Object management: Object create/inherit/clone utilities

* For the most common case:
  - replace ve.extendClass with ve.inheritClass (chose slightly
    different names to detect usage of the old/new one, and I
    like 'inherit' better).
  - move it up to below the constructor, see doc block for why.

* Cases where more than 2 arguments were passed to
  ve.extendClass are handled differently depending on the case.

  In case of a longer inheritance tree, the other arguments
  could be omitted (like in "ve.ce.FooBar, ve.FooBar,
  ve.Bar". ve.ce.FooBar only needs to inherit from ve.FooBar,
  because ve.ce.FooBar inherits from ve.Bar).

  In the case of where it previously had two mixins with
  ve.extendClass(), either one becomes inheritClass and one
  a mixin, both to mixinClass().

  No visible changes should come from this commit as the
  instances still all have the same visible properties in the
  end. No more or less than before.

* Misc.:
 - Be consistent in calling parent constructors in the
   same order as the inheritance.
 - Add missing @extends and @param documentation.
 - Replace invalid {Integer} type hint with {Number}.
 - Consistent doc comments order:
   @class, @abstract, @constructor, @extends, @params.
 - Fix indentation errors
   A fairly common mistake was a superfluous space before the
   identifier on the assignment line directly below the
   documentation comment.
   $ ack "^ [^*]" --js modules/ve
 - Typo "Inhertiance" -> "Inheritance".
 - Replacing the other confusing comment "Inheritance" (inside
   the constructor) with "Parent constructor".
 - Add missing @abstract for ve.ui.Tool.
 - Corrected ve.FormatDropdownTool to ve.ui.FormatDropdownTool.js
 - Add function names to all @constructor functions. Now that we
   have inheritance it is important and useful to have these
   functions not be anonymous.

   Example of debug shot: http://cl.ly/image/1j3c160w3D45

   Makes the difference between

   < documentNode;
   > ve_dm_DocumentNode
     ...
     : ve_dm_BranchNode
       ...
       : ve_dm_Node
         ...
         : ve_dm_Node
           ...
           : Object
             ...

   without names (current situation):

   < documentNode;
   > Object
     ...
     : Object
       ...
       : Object
         ...
         : Object
           ...
           : Object
             ...

   though before this commit, it really looks like this
   (flattened since ve.extendClass really did a mixin):

   < documentNode;
   > Object
     ...
     ...
     ...

   Pattern in Sublime (case-sensitive) to find nameless
   constructor functions:
   "^ve\..*\.([A-Z])([^\.]+) = function \("

Change-Id: Iab763954fb8cf375900d7a9a92dec1c755d5407e