PDFBOX-2549: TIFF SUB predictor for 16bpc

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1643881 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-2542: Removed check for Type of page tree root

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1643915 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-2546: PageIterator should be recursive

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1643933 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-2550: allow indirect object and avoid ClassCastException in getColour()

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1643996 13f79535-47bb-0310-9956-ffa450edef68