implements IDEA-25
Tell IDEA about custom Jangaroo ActionScript annotations
http://jangaroo.myjetbrains.com/youtrack/issue/IDEA-25

Provide a copy of IDEA's "KnownMetaData.dtd", extended
by Jangaroo's custom ActionScript annotations like [Native],
[Accessor], [ExtConfig] and [RestResource].
This even contains some documentation of the annotations.