[Qexo-general] improved handling of xml errors

[Per Bothner]

I checked into CVS various changes to improve handling
of errors when parsing XML documents.

For example here is a stack trace for when an XQuery programs
calls the document function on an xml file with errors:

gnu.text.SyntaxException: document function read invalid XML
/Users/bothner/pics/2003/NelsonCoveMarLate/index.xml:3:5: missing name
/Users/bothner/pics/2003/NelsonCoveMarLate/index.xml:6:5: </yyy> 
matching <xx>
/Users/bothner/pics/2003/NelsonCoveMarLate/index.xml:9:3: missing name
        at gnu.kawa.xml.Document.parse(Document.java:58)
        at gnu.kawa.xml.Document.parse(Document.java:66)
        at gnu.kawa.xml.Document.apply1(Document.java:72)
        at pictures.apply(pictures.xql:289)
        at gnu.mapping.CallContext.runUntilDone(CallContext.java:238)
        at gnu.expr.ModuleBody.runAsMain(ModuleBody.java:89)
        at pictures.main(pictures.xql)
--
        --Per Bothner
address@hidden   http://per.bothner.com/