Use these procedures for testing whether an object is a character set,
or whether several character sets are equal or subsets of each other.
char-set-hash can be used for calculating a hash value, maybe for
usage in fast lookup procedures.
#t if obj is a character set,
#t if all given character sets are equal.
#t if every character set char_seti is a subset
of character set char_seti+1.
Compute a hash value for the character set cs. If bound is given and non-zero, it restricts the returned value to the range 0 … bound - 1.