JSDuck: Generated code documentation!

See CODING.md for how to run it.

Mistakes fixed:
* Warning: Unknown type function
  -> Function
* Warning: Unknown type DOMElement
  -> HTMLElement
* Warning: Unknown type DOM Node
  -> HTMLElement
* Warning: Unknown type Integer
  -> Mixed
* Warning: Unknown type Command
  -> ve.Command
* Warning: Unknown type any
  -> number
* Warning: Unknown type ve.Transaction
  -> ve.dm.Transaction
* Warning: Unknown type ve.dm.AnnotationSet
  -> ve.AnnotationSet
* Warning: Unknown type false
  -> boolean
* Warning: Unknown type ve.dm.AlienNode
  ve.dm doesn't have a generic AlienNode like ve.ce
  -> Unknown type ve.dm.AlienInlineNode|ve.dm.AlienBlockNode
* Warning: Unknown type ve.ve.Surface
  -> ve.ce.Surface
* ve.example.lookupNode:
  -> Last @param should be @return
* ve.dm.Transaction.prototype.pushReplace:
  -> @param {Array] should be @param {Array}
* Warning: ve.BranchNode.js:27: {@link ve.Node#hasChildren} links to non-existing member
  -> (removed)
* Warning: ve.LeafNode.js:21: {@link ve.Node#hasChildren} links to non-existing member
  -> (removed)

Differences fixed:
* Variadic arguments are like @param {Type...} [name]
  instead of @param {Type} [name...]
* Convert all file headers from /** to /*! because JSDuck tries
  to parse all /** blocks and fails to parse with all sorts of
   errors for "Global property", "Unnamed property", and
  "Duplicate property".
  Find: \/\*\*([^@]+)(@copyright)
  Replace: /*!$1$2
* Indented blocks are considered code examples.
  A few methods had documentation with numbered lists that were
  indented, which have now been updated to not be intended.
* The free-form text descriptions are parsed with Markdown,
  which requires lists to be separated from paragraphs by an
  empty line.
  And we should use `backticks` instead of {braces} for inline
  code in text paragraphs.
* Doc blocks for classes and their constructor have to be
  in the correct order (@constructor, @param, @return must be
  before @class, @abstract, @extends etc.)
* `@extends Class` must not have Class {wrapped}
* @throws must start with a {Type}
* @example means something else. It is used for an  inline demo
  iframe, not code block. For that simply indent with spaces.
* @member means something else.
  Non-function properties are marked with @property, not @member.
* To create a link to a class or member, in most cases the name
  is enough to create a link. E.g. Foo, Foo.bar, Foo.bar#quux,
  where a hash stands for "instance member", so Foo.bar#quux,
  links to Foo.bar.prototype.quux (the is not supported, as
  "prototype" is considered an implementation detail, it only
  indexes class name and method name).
  If the magic linker doesn't work for some case, the
  verbose syntax is {@link #target label}.
* @property can't have sub-properties (nested @param and @return
  values are supported, only @static @property can't be nested).
  We only have one case of this, which can be worked around by
  moving those in a new virtual class. The code is unaltered
  (only moved down so that it isn't with the scope of the main
  @class block). ve.dm.TransactionProcessor.processors.

New:
* @mixins: Classes mixed into the current class.
* @event: Events that can be emitted by a class. These are also
  inherited by subclasses. (+ @param, @return and @preventable).
  So ve.Node#event-attach is inherited to ve.dm.BreakNode,
  just like @method is.
* @singleton: Plain objects such as ve, ve.dm, ve.ce were missing
  documentation causing a tree error. Documented those as a
  JSDuck singleton, which they but just weren't documented yet.
  NB: Members of @singleton don't need @static (if present,
  triggers a compiler warning).
* @chainable: Shorthand for "@return this". We were using
  "@return {classname}" which is ambiguous (returns the same
  instance or another instance?), @chainable is specifically
  for "@return this". Creates proper labels in the generated
  HTML pages.

Removed:
* @mixin: (not to be confused with @mixins). Not supported by
  JSDuck. Every class is standalone anyway. Where needed marked
  them @class + @abstract instead.

Change-Id: I6a7c9e8ee8f995731bc205d666167874eb2ebe23