directory, elsewise just make assumtion that pkunzip.zip is on
the PATH somewheres, and then unzip it, and then run it.
Most of this commit message is wildly inaccurate.

Crappy argument parsing.  Command line parameters are now:
-release=sbbs317 -defaults
If -release omitted, 'master' archive will be fetched.
If -defaults specified, installation will proceed without prompts and all default values will be accepted.

Accept a git tag as an argument to the script.  sbbs317 will download the Synchronet BBS 3.17 compatible release.  If absent, the master archive will be fetched.

Extract zip to temp dir, move files around, clean up after yourself, don't clobber custom pages or sidebar modules.
More prompts, including an 'enable ftelnet' option that isn't actually used for anything yet.
Update sbbs.ini RootDirectory and ErrorDirectory last of all; should trigger recycle.
Install path is system.exec_dir + ../webv4. Rather than move stock components out of the way, we'll just make a new space.  People who installed to, say, system.exec_dir + ../web will need to migrate content; instructions forthcoming.

Some error handling.
Some prompting for settings.

To-do:
- prompt for guest username, with default
- prompt for ftelnet enable/disable (and implement enable/disable)
- prompt for ftelnet splash .ans if enabled
- add WS/WSS services if missing, and if ftelnet enabled
- nuke old websocket telnet/rlogin proxies if configured
- copy web/pages/examples/* to web/pages/ (once pages has been moved out of docroot)
- likewise for web/sidebar/examples/*
- test for download/extract/ini-update success before proceeding to next step
- provide URL/info re: further config instructions upon exit

Fulfill prophecy left in a comment several years ago and actually search for the appropriate cookie.

Use Path header from client if it matches a hostname and port in modopts.ini [web] allowed_ftelnet_targets list.

If no rlogin/telnet interface specified in sbbs.ini [BBS], connect to 127.0.0.1, otherwise connect to specified address.

Added the js-date-format.js library to allow a bit of flexibility in the
way dates are displayed in the userlist.