debian/control: bump standard version
debian/watch: adding a watch file
debian/control: fixing Vcs URLs
debian/control: remove dep on Iceowl

Mozilla is no longer providing Lightning (rebranded as 'Iceowl' inside Debian)
as a standalone application. The package Iceowl was removed by ROM #742946.
debian/control*: adopting package description

As Iceowl is gone changing the package description to now the only
related package iceowl-extension.
Imported Upstream version 2.6.5
Merge tag 'upstream/2.6.5' into debian/sid

Upstream version 2.6.5
rebuild patch queue from patch-queue branch