Minor bugfixes

Fixes #465 and implements #464.

Extended Redaction Annotation support

A number of issues are also being fixed with this release:
#447, #461, #397, #463, #454, #434

Support for PDF Redaction Annotations

This release fixes issues #344, #426, #434, #443, #444.

Fixing issues with annotations

Fixing issues #415, #417 and #421.

Fixing several minor issues

This fixes #412, #411 and #407 and also inroduces some minor usability enhancements.

Introducing "fitz as a module"

Various fixes

Fixing #394

fixes #394

Fix #390

1.16.6

upload v1.16.6

Fix #381 part 2

On rare occasions, page rendering and text extraction caused interpreter segmentation faults.
When fonts on a page (illegally) were meeting all of the following conditions:

1. a non-UTF8 encodable name
2. not embedded in the PDF
3. using Identity-H / Identity-V ancoding

Then MuPDF reacted with appropriate warning messages (which are intercepted by PyMuPDF).
In prior versions, PyMuPDF did not expect non-UTF8 messages and used a too "optimistic" char to unicode conversion method, which brought down the interpreter.
This has changed in the new version.

Fixing #381

also new generators for document pages and page annotations, widget and links.