PDFBOX-2520: don't automatically decrypt encrypted pdfs, this shall be done by the parser/user before using PDFTextStripper

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/branches/1.8@1641449 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-2521: don't throw IOException in lenient mode if stream length is missing

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/branches/1.8@1641458 13f79535-47bb-0310-9956-ffa450edef68