Avoid loading a character more than once if a request is already in flight. Also ensure that more exotic Hanzi are recognized and such and get a SVG rendering. Also add stroke and character data for ⻊and ⽱.
Additionally, make the JSONP loading mechanism more robust against weird characters. Instead of having one callback per character, we now use a global hd (hanzi-data) function, which takes the char as first parameter and the data as second. Previously, we used ⻊ and ⽱ as function names, which resulted in syntax errors.