D.14.4 mpfr binary predicates

These predicates take a pair of mpfr numbers (x,y) as arguments and perform a logical operation. If the result is true, they return (nil,nil), and if it's false, they return nil.

• equal_p
• unequal_abs
• greater_p
• greaterequal_p
• less_p
• lessequal_p
• lessgreater_p

The name of the function unequal_abs, for comparing absolute values, has been changed from mpfr_cmpabs to avoid confusion with the virtual machine's compare combinator. The compare combinator returns a (nil,nil) result (i.e., true) if the operands are equal and a nil result if they're unequal, opposite from unequal_abs.