It was inconsistent that when parsing <a:foo> elements, A_TOKEN(foo) was
available, but for <w:foo> elements there was no W_TOKEN() macro.

Also, there were two manual variants (NMSP_doc|XML_foo or via
OOX_TOKEN(doc, foo)), replace both of them with W_TOKEN() for easier
searching.

Change-Id: Ic5cd027f07518535b92671ffe3c486016a3f9f0a