Support for soft-hyphens - image() can now insert .svg files - deprecating font caching

Added

• support for soft-hyphen (\u00ad) break in write(), cell() & multi_cell() calls - thanks @oleksii-shyman & @gmischler!
  Documentation: Line breaks
• new documentation page on Emojis, Symbols & Dingbats
• documentation on combining borb & fpdf2: Creating a borb.pdf.document.Document from a FPDF instance

Changed

• write() now supports soft hyphen characters, thanks to @gmischler
• fname is now a required parameter for FPDF.add_font()
• image() method now insert .svg images as PDF paths
• the defusedxml package was added as dependency in order to make SVG parsing safer
• log level of _substitute_page_number() has been lowered from INFO to DEBUG

Fixed

• a bug when rendering Markdown and setting a custom text_color or fill_color
• a bug in get_string_width() with unicode fonts and Markdown enabled,
  resulting in calls to cell() / multi_cell() with align="R" to display nothing - thanks @mcerveny for the fix!
• a bug with incorrect width calculation of markdown text

Deprecated

• the font caching mechanism, that used the pickle module, has been removed, for security reasons,
  and because it provided little performance gain, and only for specific use cases - cf. issue #345.
  That means that the font_cache_dir optional parameter of fpdf.FPDF constructor
  and the uni optional argument of FPDF.add_font() are deprecated.
  The fpdf.fpdf.load_cache function has also been removed.

To be extra clear: uni=True can now be removed from all calls to FPDF.add_font().
If the value of the fname argument passed to add_font() ends with .ttf, it is considered a TrueType font.