[CSCN] Roman Numeral Chord BB Code Support

NOTICE: You must manually add BBCode buttons to editor toolbars through AdminCP.

With this addon installed, an XenForo forum can allow users to type roman numeral chord contents to communicate harmoniology matters with each other. It supports chord symbols used in both British Royal Conservatory system and Shimaoka Harmoniology system. See the attached picture as an example:

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