- update to 1.21.1:
* Garbage collection problem causing file bloat on clean
* Don't assume sorted objects in pdf_objcmp
* Don't layout empty documents
* Type 3 font char bboxes
* Added MOBI input format support
* Added Story API for creating PDF documents from formatted text
* Added API to create, edit, and delete links
* Support custom images for Stamp annotations
* Support interior color on Polygon annotations
* Support line endings on PolyLine annotations
* Improved SVG output
* C++/Python/C# binding:
* Changes to naming of wrapper functions and classes
* Added limited support for callbacks into Python, using SWIG Directors