Both Page and Tree can now use these common methods without implementing
their own.

Giving warinings for other types.

The to_html method currently creates the top section of page.
Definitely quite buggy, but at least we have started it.

JsDuck.write_tree now also outputs empty Docs.icons object,
which keeps UI from crashing - but we should fill it with
actual icons-map in the future.

--output now specifies output directory.  The tree is now written to
  file instead of stdio.
--verbose turns on printing of parsing progress.

JsDuck::Tree creates from doc-object list a tree structure consisting
of Ruby Hashes and Arrays.  Another method in jsduck.rb converts this
to JSON and outputs.

For all this added a unit test, but with it's single test it's mostly
just a sanity check.

The previous debug output was removed to separate method.

jsduck script now reads filenames from command line, parses each one
of them and prints out tree of classes and their properties.

Not quite correct, but for now it's better for them to behave the same.

Again one of the most used @tags in ExtJS.

Only supporting it in class declaration, plus some explicit logic to
detect it when it appears after @constructor in class doc-comment.

Applies only to properties and methods.

This was one of the most used @tags in ExtJS not already supported by
JsDuck.

Class member arrays are now named the same as their tagnames.
So we access class configs with  class[:cfg]  rather than with
class[:cfgs]

All the complex comment and code analyzing is now done by Merger class,
the doc_comment_parser now just parses input into a linear array of at-tags.
The Merger completely replaces DocComment class and most of the complex
work in DocCommentParser.

Most of the tests are now also at top level tc_jsduck - so that we
mainly test the whole jsduck module, allowing the internal classes to be
more easily reorganized.

@ignore and @hide are now simply aliases of @private.

The results of DocComment and JavaScript parsing are merged together in
top-level parse method.

Devided files between lib/ and test/ directories.
Added Rakefile that runs all the tests.

The most important at-tags are now supported.

These abstract away the repeated code for parsing:

    @sometag {type} name ...

Plus refactoring of the similar behaviour in @method and @property to a
function.

Simpler, more robust, and correct now.

It's silly that @class must always be before class description,
but @method can either be before or after the description.

To comply with ext-doc.

Both @singleton and @extends now imply that the preceding description
must be a description of a class.

Therefore simplified the logic in set_default_name() method.

Only the comment may span several lines.

This means we can just say:

  /**
   * @cfg
   * True to enable this component.
   */
  enabled: false,

Previously this meant that we declared cfg with name "True",
but now the name cannot come after newline, so we can leave the
name out of the doc-comment and infer it from the source.

Parser enhancements to be able to infer @cfg and @event name from code.

DocComment enhancements to be able to set the name of at-tags other than
the default.

Meaning that when doc-comment contains @class followed by @cfg
and @event, then three tagsets are returned.