Also tuned the expandability detection algorithm.  Now all items
with extra_doc are expandable, and the short version never contains
extra_doc.  Plus the ellipsis is only shown when the primary_doc
is shortened.

As there is next going to be LongParams.

Removed parameter list creation code from Table class as it's
only needed for EventTable and MethodTable - so it's now in
separate class that only those table-classes use.

The rest of the signature is pretty standard.

Currently ignoring the link href value in signature -
as we currently don't output source files.

Each documentation table type is now created by separate class.
Common functionality being defined in baseclass JsDuck::Table.

But still avoiding "stupid expansions".

Stripping HTML tags from short versions of doc-rows.

My test-data is now mainly the ExtJS framework source.

Eventually I would like to move all unit tests to rspec.

Implemented Class.inherits_from? through which we check if
class inherits from Ext.Component (or if needed, from any other
class).

Unlike in ext-doc we mark the Ext.Component itself also with component
icon.  It always had bothered me that the base component itself was
not easily identifiable as component.

Previously they were interpreted as empty doc-comments.

The same method now retrieves all members of a class:
  :cfg, :method, :property, and :event.

Plus minor Merger enhancement - Missing name is now an empty string,
not nil.

Including the ones belonging to parent classes.
All methods are augmented with :member field that
says the class they belong to.

In top-level filter_classes each Class instance
also receives a hash of all classes - so that the
Class.parent() method can return instance of parent class.

Finally added some rudimentary tests for all this.

Introduction of ident/keyword separation broke this before,
now it's working again.

Another regex v/s division tokenization enhancement.