- Allow boxes_flow LAParam to be passed as None, validate the input, and update documentation ([#395](https://github.com/pdfminer/pdfminer.six/pull/395))
- Removed samples/issue-00152-embedded-pdf.pdf because it contains a possible security thread; a javascript enabled object ([#364](https://github.com/pdfminer/pdfminer.six/pull/364))
- Support for extracting JBIG2 encoded images ([#311](https://github.com/pdfminer/pdfminer.six/pull/311) and [#46](https://github.com/pdfminer/pdfminer.six/pull/46))
- Refactor `LTLayoutContainer.group_textboxes` for a significant speed up in layout analysis ([#315](https://github.com/pdfminer/pdfminer.six/pull/315))
- Contribution guidelines in [CONTRIBUTING.md](CONTRIBUTING.md) ([#259](https://github.com/pdfminer/pdfminer.six/pull/259))
- Support new encodings OneByteEncoding and DLIdent for CMaps ([#283](https://github.com/pdfminer/pdfminer.six/pull/283))
### Fixed
- Use `six.iteritems()` instead of `dict().iteritems()` to ensure Python2 and Python3 compatibility ([#274](https://github.com/pdfminer/pdfminer.six/pull/274))
- Properly convert Adobe Glyph names to unicode characters ([#263](https://github.com/pdfminer/pdfminer.six/pull/263))
- Allow CMap to be a content stream ([#283](https://github.com/pdfminer/pdfminer.six/pull/283))
- Resolve indirect objects for width and bounding boxes for fonts ([#273](https://github.com/pdfminer/pdfminer.six/pull/273))
- Actually updating stroke color in graphic state ([#298](https://github.com/pdfminer/pdfminer.six/pull/298))
- Interpret (invalid) negative font descent as a positive descent ([#203](https://github.com/pdfminer/pdfminer.six/pull/203))
- Correct colorspace comparision for images ([#132](https://github.com/pdfminer/pdfminer.six/pull/132))
- Allow for bounding boxes with zero height or width by removing assertion ([#246](https://github.com/pdfminer/pdfminer.six/pull/246))
- All dependencies are managed in `setup.py` ([#306](https://github.com/pdfminer/pdfminer.six/pull/306) and [#219](https://github.com/pdfminer/pdfminer.six/pull/219))