Table improvements, bidirectional text support, support for <path> in SVG and several bug fixes

Added

• support for <path> elements in SVG <clipPath> elements
• support for bidirectional text shaping - thanks to @andersonhc
• documentation on how to combine fpdf2 with mistletoe in order to generate PDF documents from Markdown (link)
• tutorial in Dutch: Handleiding - thanks to @Polderrider
• support for Table cells that span multiple rows via the rowspan attribute, which can be combined with colspan - thanks to @mjasperse
• TableSpan.COL and TableSpan.ROW enums that can be used as placeholder table entries to identify span extents - thanks to @mjasperse

Fixed

• when adding a link on a table cell, an extra link was added erroneously on the left. Moreover, now FPDF._disable_writing() properly disable link writing.
• FPDF.write_html() now handles linking directly to other pages - thanks to @mjasperse
• non-bold TitleStyle is now rendered as non-bold even when the current font is bold
• calling .table() inside the render_toc_function
• using .set_text_shaping(True) & .offset_rendering()
• fixed gutter handing when a pagebreak occurs within a table with header rows - thanks to @mjasperse
• fixed handling of border=0 in HTML table - thanks to @mjasperse
• FPDF.write_html() now properly honors align= attributes in <th> tags
• fixed problem using bold italic standard fonts in markdown - thanks to @Alan-Collins

Changed

• refactored FPDF.multi_cell() to generate fewer PDF component objects - thanks to @mjasperse
• outer table borders are now drawn continuously for nonzero gutter_width/gutter_height, with spacing applied inside the border similar to HTML tables - thanks to @mjasperse - cf. #1071
• removed the requirement that all rows in a Table have the same number of columns - thanks to @mjasperse

Deprecated

• font aliases (Arial → Helvetica, CourierNew → Courer, TimesNewRoman → Times). They will be removed in a later release.