Version 2.2.3 - 07 January 2023  Qt.core.  Minimum Calibre Version: 6.0.0
Version 2.2.2 - 03 February 2021 Translation to Spanish.
Version 2.2.0 - 17 December 2020 Miscellaneous technical changes to improve performance.
Version 2.1.9 - 19 December 2019 Technical changes after Python 3.8 testing with Calibre 4.99.2
Version 2.1.8 - 16 December 2019 Technical Tweaks after compiling with Python 3.8
Version 2.1.7 - 22 July  2019 Technically restructured and simplified to improve performance.
Version 2.1.6 - 23 May 2019 Python 3 compatibility.
Version 2.1.5 - 05 May 2017 Allow themes with user-defined icons.
Version 2.1.4 - 16 May 2016 Changes for use by the Favourites Plug-in.
Version 2.1.3 - 22 June 2015 Changes to make ABC consistent with ABCH
Version 2.1.2 - 22 June 2015 Improved user experience when executing repetitively in multiple Calibre libraries continuously.
Version 2.1.1 - 21 June 2015 Miscellaneous performance tweaks.
Version 2.1.0 - 6 June 2015 Many Technical Changes to Improve Performance and Ease of Use.
Version 2.0.2 - 5 September 2014 Change due to Calibre 2.2.0 code changes.
Version 2.0.1 - 24 August 2014 increased max book count from 500 to 5000
Version 2.0.0 - 7 August 2014 Added optional new custom column abc_numeric
Version 1.1.0 - 28 July 2014 Technical and Functional enhancements.
Version 0.1.0 - 21 June 2014 Initial version of this plugin.