Tests that XD0006 is raised when more than one document arrives on a non-sequence port
Test ab-err-d0006-002.xml is expected to fail with error code err:XD0006.
<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
   <p:output port="result">
   <p:add-attribute match="/doc" attribute-name="att" attribute-value="val">
      <p:with-input>
         <p:inline>
            <doc/>
         </p:inline>
         <p:inline>
            <doc/>
         </p:inline>
      </p:with-input>
   </p:add-attribute>
</p:declare-step>
Some new and some changed tests
Fix namespace declarations
More tests.