Refactored to fix 3 implementation smells

[ashishbhasin45]

1. Decompose complex conditional.
   Location- Sub-project: imixs-workflow-core
   Package: org.imixs.workflow.xml
   class: XMLItem
   Method: stripNonValidXMLCharacters

2. Renamed the variable in the specified method from o to a currentReportItemValue for better understandability.
   Location- Sub-project: imixs-workflow-engine
   Package: org.imixs.workflow.engine
   Class: ReportService
   Method: updateReport

3. Decomposed parseTag method to resolve a complex method code smell for readability and understandability.
   Location- Sub-project: imixs-workflow-core
   Package: org.imixs.workflow.util
   class: XMLParser
   Method: parseTag

[rsoika]

Thanks for your contribution!
Yes it was not the the best code ;-)
As we this part is covered by a lot of unit tests we can submit it. Please only add my method comment.