editors/zim: Update to 0.73.1

(Update prepared in wip by Matthias Petermann)

Upstream changes:

* New features added:

  * A Recent Changes dialog and a Recent Changes pathbar option
  * A search entry in toolbar
  * An option for custom commands to replace the current selection
  * A table plugin
  * Support for Fossil version control
  * An option for linenumbers option in insert code block dialog
  * An option to display date column in tasklist side pane
  * An option to set the wrap-mode in sourceview
  * A theme choice for the source view plugin
  * A "private" switch to server command for commandline usage
  * Authentication support to web server
  * A template selection option to web server dialog
  * An option for fontsize to table of contents plugin
  * An option to show horizontal lines in table of contents
  * Ability to combine formatting styles in editor

Platform / general changes:

  * Ported zim to use Python3 & Gtk3
  * A lot of bug fixes and performance improvements

For full change log please refer to:
  
  https://github.com/zim-desktop-wiki/zim-desktop-wiki/blob/master/CHANGELOG.md
