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.

Plus some logic to set_default_name to prevent @cfg-s and @event-s
from becoming functions.

@constructor is equivalent of @function with name "constructor".

The Parser now brings Lexer and DocComment together.

- Moved some more tests to Lexer testsuite.
- The :doc_comment part of it is now more easily testable.
- Additionally assert_tokens now checks the nr of tokens.

Accordingly found and fixed some string and regex parsing errors.

Additionally supporting numbers now too.

Now doing a proper recursive-descent parsing of the code following the
doc-comment.  After that, having the parsed structure it's a lot easier
to inspect it and add info to the doc-comment data as needed.

Also implemented auto-detection of superclass when Ext.extend() is
used.

At tags are now tested in order they most likely appear in source code:

@class -> @function -> @param -> @return

Also, when function name begins with uppercase letter, it's assumed to be
class name.