Use the common Comments.avatar method to generate the <img> tag,
giving us the same default avatar that we use everywhere.

Also toggle the subscription checkbox depending on the status
of subscription in commenting form.

The guide config can now contain an "url" field which by default
points to guides/<guide-name> but can be configured to point at anything
desirable.

Remove an old restriction left over from the days when JSDuck didn't
show private members at all.

Only when the enum is an auto-expanded list of alias values
or when it's defined as array - only then show the warning.

The :config_file task generates initial simple sdk-vars.rb config.

The :configure runs both :get_extjs and :config_file, doing the
initial setup for running jsduck.

This should help tools like readability.com extract the contents
of the page.

So we detect the constructor the same way.

It's quite obvious what constructors do.

Also added a method Class.constructor? to check if a member is
a constructor function.

This ensures that when running the export repeatedly the order
of mixins/requires/etc will stay the same.  Especially in the
case of mixins which are often defined in an object literal which
gets turned into a Ruby hash that messes up the order quite a bit.

By doing the sorting in Export::Full the Renderer no more needs
to sort these things.

Make it work with renamed Json class.

Print also those classes that are exactly the same.

Point it now to Github instead of Sencha forums.