Things to do
============

User-defined functions

Read script, especially at start-up

Error checks for math functions are probably incomplete, and
need filling out.

Provide line editor history

Add other line editing functions (end of line, kill line, etc)

check ctrl-c in line editor

Implement SIGFIG properly, to take a number, not just a digit. Then
modify kc_fmt to work with precisions > 9 figures.

Provide a way to set how large/small a number must be, before using
scientific notation, independent of the precision

Provide an engineering output format ("1k2" rather than "1.2E3")

