Most of our sites are now HTTPS-only. Update URLs accordingly. Update
other URLs while we're at it. Remove or comment out dead links.

Change-Id: I7c4f323e6585d22760bb90bf28fc0faa6b893a33
Reviewed-on: https://code.wireshark.org/review/7621


Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Gerald Combs <gerald@wireshark.org>