Pdfnaut

This update adds support for encoding and encrypting objects.

Additions:

- All filters (except Crypt) now support encoding.
- Added a decoder for the RunLengthDecode filter
- The security handler was reworked to allow for encryption of objects.

Removals:

- The TIFF predictor function used previously was implemented improperly. It has now been removed.

Fixes:

- The PNG predictor function previously worked on entire samples rather than on bytes, which led to only one of the color components being preserved. This has now been fixed.

A small update that adds two additions
- Incremental updates are now exposed under a new `updates` attribute in the PDF parser. See the docs for info.
- An edge case was found when attempting to tokenize an indirect reference at the end of data. This has now been fixed.

The first release of pdfnaut. Available on [PyPI](https://pypi.org/project/pdfnaut/0.1.0/).