Important fixes, some improvements for drawing extraction

• fixed #692
• fixed #686
• Added transparency options for various methods in classes Shape and Page.

Support MuPDF v1.18.0

This version fixes the following issues:

• #519 - method Page.cleanContents() should no longer destroy the PDF page's appearance. In earlier versions, this upstream bug occurred in rare cases.
• #675 - unsuccessful storage allocations (e.g. for extremely large pixmaps), could occasionally lead to interpreter crashes. This should now always be prevented (fingers crossed).
• #668 - the specification of line dashes in PDF is now correctly documented.
• #669 - fixed a major cause of memory leakage in method Document.insertPDF.

The following new features or improvements are included:

• Text extraction method Page.getText() now also works for annotations: Annot.getText().
• Text from within a rectangle can now be extracted directly via Page.getTextbox(rect). This may obsolete extra scripts in many cases.
• When applying redactions on PDF pages, the handling of images can now be fine-controlled via a new parameter.
• The DPI (resolution) of PNG images created from pixmaps is now automatically set from the Pixmap.xres and Pixmap.yres values.

Fixes, performance improvements

Fixed #651
Fixed #645
Fixed #622
Fixed #653
Fixed #640
Added methods and atrributes to speed up TOC maintenance.
Added new page method to extract text from inside a rectangle.
All getText() methods (except (X)HTML and XML) now support a clip parameter.

Bug fixes and more support for font replacements

• Fixed #605
• Fixed #600
• Added origin key to text span dictionary of Page.getText("dict").
• Added property buffer to fitz.Font.
• Added option sanitize to Page.cleanContents().

Several fixes

• Fixes #561
• Fixes #566
• Fixes #568
• Correct use of opacity default in TextWriter.writeText().
• Supporting fonts of [pymupdf-fonts(https://github.com/pymupdf/pymupdf-fonts).
• Some smaller feature improvements.

Font Handling improvements and other fixes

Fixes #561 - more than 10 TextWriter fonts per page
Fixes #562 - annotation pixmaps no longer derived from tha page
Fixes wrong appearance of mono-spaced fonts
Resolves #563 - allow manipulation of PDF property NeedAppearances
Support optional fonts provided via repository pymupdf-fonts

Minor Fixes, more flexible TextWriter Textbox

Fixes #540
Fixes #548
TextWriter.fillTextbox now supports indenting start of text.

Fix Important issue

Fixes #533
Adds appearance flexibility to redactions annotations, #535.

Addressing minor bugs

Fixed: #525, #520
Implemented: #524

Improved interactive help a lot.

Supporting MuPDF v1.17

• Improved Redaction annotation support.
• Fixing #508, #503, #502, #500, #496
• Minor feature enhancements