Fix XML Output for Resources with Control Chars

[alexanderkiel]

If resources contain control characters like \u001e (record separator) in strings or other string like primitive type values, the XML generator can't output them. Because the resulting exception is not handled, the output hangs and will never finish.

A fix should contain the following:

• handle exceptions while generating XML
• disallow control chars in primitive type values like strings, codes, URI's and so on