Clarify remaining maximum occurrences

I didn't realize that the default for an unspecified maxOccurs is 1,
not "unbounded."  This rendered the use of "##other"-namespace elements
limited to a clearly incorrect degree.

This patch clarifies all remaining min/max element occurrences, found
with:

    grep minOccurs dfxml.xsd | grep -v maxOccurs

Except, one is left unspecified: the upper bound on <byte_run> elements
is in a proposed revision here:
<https://github.com/dfxml-working-group/dfxml_schema/issues/5>.

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
Allow other-namespace attributes on all DFXML elements

Somebody asked if the all elements could be made extensible:
<https://github.com/dfxml-working-group/dfxml_schema/pull/9#issuecomment-25035429>

In response, this patch defines wrapper types for all the basic "xs:"
types DFXML elements use, adding an anyAttribute extension.  Now any
element in DFXML can have an attribute from other namespaces.

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
Allow partition_offset to be 0

It's sometimes appropriate for the offset to be 0, for instance, when
analyzing a partition image.

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
Allow other-namespace elements in one more fileobject location

Until a DFXML schema 1.1 validator is found, there is no graceful way to
allow other-namespace elements to appear in any order for elements.
This patch, pretty much one for aesthetics, allows the other-namespace
elements to appear immediately before the often-immense lists.

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
Batch changes into v1.1.0rfc5

This updated RFC version completes other-namespace extensibility for
DFXML elements, corrects some logical representation errors, and adds
flexibility for extension element locations.

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>
Merge pull request #13 from ajnelson/archive/for_v1.1.0rfc5_seriesv1

For v1.1.0rfc5, patch series version 1

Acked-by: Mark Matienzo <mark.matienzo@gmail.com>