PDFBOX-2469: avoid calling InputStream#available as proposed by Thomas Chojecki

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/branches/1.8@1641210 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-1648: improve the CMapParser to detect missing delimiters as proposed by May Gilead and Kevin Pearcey

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/branches/1.8@1641219 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-2517: improve error messages

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/branches/1.8@1641325 13f79535-47bb-0310-9956-ffa450edef68