Using only Amiga Dos script language, pops a requstor that lets the user
enter a number digit-by-digit (like on a calculator) by clicking with the
mouse, lets you change the sign of the number, delete digits already
entered, and clear the number.  Also lets you specify a Max, Min, and
Default number when executing it.  Returns value to StdOut and in $cntot.
It's a bit slow and ugly, but it works.

Will not work with Dos 1.3, may work with 2.0+, WILL work with 3.0+.
(Requires eval and requestchoice commands that come with Dos 3.0+ and
maybe 2.0+, I don't have 2.0 so I don't know)

 PERMSSN    UID  GID    PACKED    SIZE  RATIO     CRC       STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                 1231    2548  48.3% -lh5- 5109 Jun 10  1995 ClickNumber
[generic]                  424     745  56.9% -lh5- 9b6f Jun 10  1995 ClickNumber.readme
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total         2 files    1655    3293  50.3%            Jun 10  1995