Parsoid outputs rel="mw:wikiLink" or rel="mw:extLink", so we convert that to link/wikiLink and wiki/extLink respectively.
Also preserve the data-mw attribute; we probably need to do this more generally but this'll do for now.
Change-Id: I32e570bffa5a73a733a120d52cfd8b75d3191e02
* Added converters to all relevant node implementations
* Added new annotation objects with their own factory
Change-Id: I9870d6d5eac45083929d74d2e58917d0939ca917