1.3 version released

* Major reworking of the PDF export engine to make it handle exporting various combinations of a citation's main text, translation or commentary, as well as supporting exporting of citations with their translation in footnotes.
* Fixed issue with RTF export that made it impossible to export bibliographic reference codes in multiple formats.
* Fix to a bug that occasionally caused Citebook corruption when changing author and publication names
* Various other bug fixes.