these functions.

so that their initialisation order ensures they have the proper values. Add
unit tests for these constants.

and simplify the Remez code accordingly.

multiplications by integers, especially powers of two.

code shortcut, fix bugs in the addition and subtraction, another one in
the multiplication code, and add new unit tests for most of these.

to 32 bigits.

and add a test suite check for unary minus.

multiplication.