Bug 879211: ignoring bad document outline reference
Bug 874851: ignoring bad stream length
Bug 861638: ignoring double-EI
#3248: fixes hp scanner's bad XRef
#2098: scanning for stream length when it's incorrect
#1277: ignoring error for bad "empty" block
Merge pull request #3376 from yurydelendik/bad-pdfs

Misc fixes for corrupted PDFs