Backport patch #1051321 (fixes bugs 1010196, 1013525), by Mike Brown:

Backport patch #1051321 (fixes bugs 1010196, 1013525), by Mike Brown:

* Document hasFeature(), createDocument(), CreateDocumentType(),
  hasAttribute(), hasAttributeNS().

* In the documentation for createDocument(), it is now stated that the Python
  DOM API allows implementations to forego creation of the document element
  child node, if no namespace and local name arguments are given. (This
  possibility is left open and unaddressed in the W3C spec).

* Addition by me: use 'name' rather than 'attname', for consistency with the
  DOM specification and the Python DOM API implementation.