Prevent an importer from importing the same page more than once

Allow PDFs with DecodeParms less than 4

Bug fix: Failed to read xref table: Unsupported field size

Fix for 'did not set root object'

Remove spew

Update README.md

fixed import stream identifier (#11)

* fixed import stream identifier

* Update README.md

Add acknowledgements and PDF stream example

Add ability to get page sizes

Fix string parsing bug