To do
-----

0.	Bugfixes.
0.	Overflow checking for *_proc, atol and others.
0.	Output results to keyboard buffer.
1.	Improve command line parsing.
2.	Rewrite div_proc, mod_proc.  May be rewrite shr_proc, shl_proc,
	sar_proc too?
2.	Optimization.
3.	Fixed point arithmetic.
3.	Internationalization.

