"RationalNumber" class is "public"

As per its Javadoc, class RationalNumber is tuned to the requirements of the TIFF format while its name purports that it's a general implementation of the "fraction" concept.
Which is it?

Do we want that utility to be part of [Imaging]'s public API (thus eliciting support to application developers who might use it beyond its intended scope)?
A dependency on [Numbers]'s "fraction" module, as proposed in IMAGING-309) would avoid the issue, and also consolidate (and/or help find potential bugs in) [Numbers]'s implementation.

If that proposal is not accepted, RationalNumber should preferably be moved to [Imaging]'s internal package.