dellines.icn: Program to delete lines from a file

This program is designed to delete a few specified lines from a file.
The line numbers are given on the command line, the file is read from
standard input and the lines that are not deleted are written to standard
output as in

     dellines 46 23 119 <infile >outfile

which writes all lines but 23, 46, and 119 of infile (if it contains that
many lines) to outfile.

Line numbers do not have to be given in order.  Numbers less than 1 are
ignored, but a nonnumerical argument is treated as an error.