Anki add-on: Japanese Furigana+

This is a slightly modified version of the existing, and largely wonderful, JapaneseFurigana add-on. The primary difference is that it attempts to assign the minimal readings to individual kanji, rather than providing the full readings for entire morphemes. So, for instance, for 「漢字」, we attach the furigana 「かん」 to the character 「漢」, and 「じ」 to the character 「字」 (漢[かん]字[じ]), rather than attaching the reading 「かんじ」 to the entire morpheme 「漢字」 (漢字[かんじ]). While the latter may offer better readability in some circumstances, in flashcards, where the intent is to be didactic, I prefer seeing exactly which part of the reading each character contributes to the whole. That said, since both methods have their merits, this behavior is configurable via the Tools menu. The other, relatively minor, difference is that the config menu items for the add-on are relegated to their own sub-menu rather than being tacked on to the end of the Tools menu without any context.