PDFBOX-2126: reset lastClip, as proposed by Petr Slaby

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1607463 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-2179: 
* rework on error messages
* added a filter on file list

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1607464 13f79535-47bb-0310-9956-ffa450edef68