Find multibyte characters in the region specified by FROM and TO.
If FROM is a string, find multibyte characters in the string.
The return value is an alist of the following format:
((CHARSET COUNT CHAR ...) ...)
CHARSET is a character set,
COUNT is a number of characters,
CHARs are the characters found from the character set.
Optional 3rd arg MAXCOUNT limits how many CHARs are put in the above list.
Optional 4th arg EXCLUDES is a list of character sets to be ignored.