-------------------------------------------
tcl function: editfile <lutfile> -- edit current LUT
-------------------------------------------
keyboard equivalent: none

Edit the color lookup table (LUT) using a basic
editor (tries gedit,nedit,xedit in that order).
To cause the editor to be vi inside a popped-up
gterm or xterm, set this environment variable:

  setenv CSURFEDITORVIGTERM

If the file in the "lut:" field (by default,
*/$scandir/val2rgb.lut) doesn't exist when the
"E" button is clicked, a default one will be
contructed when the editor opens.
