Remove some unused code.

Update to 6.2.3.  Belatedly, I confirmed that 6.2.2 supports
Greymagic's Mozilla Disk Explorer (http://sec.greymagic.com/adv/gm001-ns/)
which demonstrates a security bug.  The demo does not work with
6.2.3.  I am assuming that the zlib double free() bug, if it existed,
may have been addressed, so I am removing the FORBIDDEN line.

I didn't bother to update the generated files for this release,
since the old ones seem to work fine.

Add hitherto forgotten PKGNAMEPREFIX so the English, French, German
and Japanese versions may all be installed without conflicting.

Update Japanese, German, and French Netscape ports to version 6.2.2
(the English port was already updated, because Netscape released
that binary before releasing the others).

Install Netscape in a different directory for each different language.
The startup command is now called netscape6english, netscape6french,
and so on, rather than just netscape6.  Because of this, I set
PORTREVISION for the English version.

Update English Netscape to 6.2.2, with unknown changes.  The French,
German and Japanese ones remain at 6.2.1.

Bump PORTREVISION for those, because of change to startup script.

Add new port of Netscape 6 (Linux binary) with Japanese localization.