Rewrite factory method to simplify it and to handle radix numbers. Move it to PsNumber.
Remove unnecessary constructor and unnecessary method.
Mark PostScript numeric classes as immutable.
Move "round" logic from the type to the operand in the system dictionary.
Add int constructor and two constants.
Use normal Java parsers for converting String to PsReal.
Eliminate dependence on double-precision computations.
Address some uses of BigDecimal.