addurl: add URLs to a bookmark page

I wrote this program to help maintain my bookmark file. Michael Slone improved it by adding a number of command line arguments and, just as importantly, a manpage. I have since modified it just a wee bit (by adding more environment variables).

The files are as follows:

• addurl (the Perl script; includes inline POD documentation)
• addurl.man (manpage, in *roff format)
• addurl.ps (manpage, in Postscript format)
• addurl.html (manpage, in HTML format)