SuperbChemistry 3.0 - Update for compatibility with modern versions of OpenOffice and LibreOffice. One of the regular expressions contained an unescaped [ in a character class, which no longer works because it now denotes a named character class. Also, work around a bug in LibreOffice undo. - Put all actions taken during a formatting pass in an undo context so they can be undone and redone as a unit. - Change the file extension to oxt and add full extension metadata and a menu item. - Add support for formatting a selection rather than the entire document, with a minor limitation. - Make the rules for recognizing sequences slightly more conservative.