Added `suppress_markup` boolean keyword to KeyCluster.

When set to True, `suppress_markup` prevents the flat and/or natural sign from
being printed above the cluster. This is useful for notating tied clusters,
where only the first cluster in the logical tie needs the markup.
Added a `transpose=False` boolean keyword to PitchClassSegment.rotate().

When set to true, the rotated pitch-class segment will be transposed to start
on the same pitch-class as the original pitch-class segment.
Adjusted StorageFormatManager.compare().

OLD:

    if type(object_one) != type(object_two):
        return False

NEW:

    if not isinstance(object_two, type(object_one)):
        return False