v1.9.0

Major changes:

• Support new commands introduced in Doxygen v1.13.0 and v1.13.1: \plantumlfile, \? and \!.
  Note: Doxygen v1.13.0 now supports the strip and nostrip options for the \dontinclude and \include commands; VSDoxyHighlighter already supported them since v1.8.0, so no changes there.
• Updated quick info documentation of all commands to Doxygen v1.13.1.

Full Changelog: v1.8.0...v1.9.0