Restrict warning category characters in tab output

to make them compatible with the Jenkins plugin parser deal

lib/report.rb

@@ -632,6 +632,7 @@ class Report
 
       checks.send(meth).map do |w|
         line = w.line || 0
+        w.warning_type.gsub! /[^\w\s]/, ' '
         "#{file_for w}\t#{line}\t#{w.warning_type}\t#{category}\t#{w.format_message}\t#{TEXT_CONFIDENCE[w.confidence]}"
       end.join "\n"