Log Message:
mupdf: Update to 1.18.0

Changes:
1.18.0
------
mutool draw: bbox output format.
mutool draw: structured text extraction in JSON format.
mutool run: StructuredText.walk()
mutool run: PDFPage.process() and PDFAnnotation.process()

mupdf-gl: Added IBM Common User Access shortcuts for copy & paste.
mupdf-gl: Improved redaction UI.

java: Example desktop Java viewer.

wasm: WebAssembly viewer that runs in a browser.

api: Dehyphenation option in structured text extraction, to improve
     searching for words that are hyphenated across lines.
api: pdf_new_date, pdf_to_date, pdf_dict_put_date and pdf_dict_get_date.
api: Added choice of image redaction algorithms: none, full, partial.
api: Optional use of Tesseract to use OCR to extract text.

svg: Many small parsing fixes.
svg: Parse inline CSS style attributes.
svg: Text elements (simple text layout only).

html: Added HTML5 parser.

pdf: High security redaction -- save redacted PDF as flattened bitmap,
     guaranteed to not leak any sensitive redacted information.

Experimental C++ bindings.
Experimental Python bindings.