itags.icn: Program to create tags file for Icon programs

Program to create a tags file for an Icon program.  It has the
options described in the Sun 3.5 man entry for ctags (except -u --
update tags file):

Usage: itags [-aBFtvwx] [-f tagsfile] file...

  -a   append output to an existing tags file.

  -B   use backward searching patterns (?...?).

  -F   use forward searching patterns (/.../) (default).

  -x   produce a list of object names,  the  line  number  and
       file name on which each is defined, as well as the text
       of that line and prints this on  the  standard  output.
       This  is  a simple index which can be printed out as an
       off-line readable function index.

  -t   create tags for records.

  -v   produce on the standard output an  index  of  the  form
       expected  by  vgrind(1).   This  listing  contains  the
       function name, file name, and page number (assuming  64
       line pages).  Since the output will be sorted into lex-
       icographic order, it may be desired to run  the  output
       through sort -f.  Sample use:
            itags -v files | sort -f > index
            vgrind -x index

  -w   suppress warning diagnostics.