Add a hook function to handle an escaped character entity.
Add a hook function to handle an escaped character entity. When an entity definition isn't one of the five supported types (>, <, &, ', "), the appropriate function you install will be called to handle the translation. You will need to add one functions for each entity encoding you want to support.
The function must return a pointer to the string to be output instead of the encoded entity. This should preferably be a static buffer. Your function will have a pointer to the first character after the ampersand as its first and only argument.