Core xml schema wd 29

[Juan Carlos Cruellas <cruellas@ac.upc.es>]

I have noticed some apparent inconsistencies between the core
doc and the xsd file for version 29. I haven't reviewed everything
but so far I have found:

1. Schema for ClaimedIdentitiy in the xsd file does not incorporate
the SupportingInfo element as indicated in the core.

2. DocumentWithSignature is defined differently in core document
and in xsd file.

Juan Carlos.