Sigil: update to 0.9.10.

Sigil-0.9.10
  Bug Fixes
    - Fix signal handling to prevent double launch of plugins immediately after plugin installed
    - Fixed incorrect named entity tooltips for many of the Insert-> Special Characters
    - Fixed lack of recognition of woff2 fonts inside Sigil and for plugins
    - Fix segfault when .xml is first file in BookBrowser and add new html or split at cursor is invoked
    - Fix bug that allowed multiple audio/video tabas of the same resource to be opened
    - Fix plugin related bug when adding/removing last xhtml file
    - Fix Text Direction setting inside body to use structural dir attribute under epub3
    - Fix duplicate group-position property in epub3 MetaData Editor
    - Use absolute path references when first opening Sigil with an ebook so that Open Recent works better
    - Fix "issue" in handling self-closing script tags in head (similar issue that we had with self-closing title tags)
    - Fix issue converting Qt Strings to their Python equivalent when outside the BMP
    - Fix issue with trying to add existing html files when names clash due to case insensitive file systems
    - Fix crash bug after styling text in BookView and immediately going to CodeView without moving cursor
    - Fix crash bugs after deleting resources contained in a Report in the BookBrowser
    - Fix bug that destroys nav if left in unparseable state by user even temporarily
    - Fix bug that moved curosr to beginning of tag block when save is done in CodeView

  New Features
    - allow plugins to supply their own icon (plugin.png 48x48) for use on the Quick Launch Toolbar icons
    - extend plugin interface to include the status of the epub inside Sigil (modified or saved)
    - extend plugin interface to include the path to the saved epub file or the null string if never saved
    - extend Insert->Special Characters to include both a Greek letter panel and a mathematical symbol panel
    - add support for calibre:series and calibre:series_index to Metadata Editor for epub2
    - add support for calibre:title_sort to Metadata Editor for epub2
    - add support for clicking internal links in Preview to load the proper destination tab
    - add support for loading Qt's base translation files if present. Allows buttons on native qt dialogs to
        be translated (Windows users may need to manually copy newer qtbase_xx.qm files to Sigil's translation
        directory if they didn't exist in Qt5.6.2)
    - allow user to add custom css rules to Preview/Book View by creating a file called "custom_preview_style.css"
        in the Sigil preferences folder (not responsible for custom css and ebook css fighting with each other)

(wiz)