Progress on broken bundled extensions

[Mark H Weaver]

Hello fellow Gnuzillians,

I've pushed several commits to the '68' branch on Savannah.  They fix
various issues, but most notably: The bundled extensions now work.
Also, I removed the IceCat-specific customization that sets
'xpinstall.signatures.required' to false.  In its place, at least for
now, IceCat will need to be configured with the more fine-grained
mozconfig option --with-unsigned-addon-scopes=app, which disables
signature checking for extensions that are bundled with IceCat.

However, there's still a problem that will affect users upgrading from
earlier preview versions of IceCat-68.  It seems that IceCat remembers
that the signature checks failed before, and memory of that problem
persists.

I know of one way to fix this problem: go to <about:support> and click
on the "Refresh IceCat..." button in the top-right box.  This will reset
your browser settings and the set of installed add-ons, while retaining
other things including: your bookmarks, browser history, saved form
history, cookies, windows and tabs.

It's probably a good idea for users to do this anyway, but ideally I
would like to find a better solution.

Anyway, this problem only affects users who had already upgraded to an
earlier preview of IceCat-68.  For first-time users, or users upgrading
from IceCat-60, the bundled extensions work properly.

Other notes on the recent batch of commits to the '68' branch:

* When opening a new private window, it now says "IceCat" instead of
  "Firefox" at the top.

* <about:rights> is fixed.

* I added Johannes Marbach's 'librify-libgen-me' extension to the set of
  bundled extensions in IceCat.  Thanks, Johannes!

For now, the only way to get these improvements is to checkout the '68'
branch on Savannah, use 'makeicecat' to build a new IceCat tarball, and
make sure to add --with-unsigned-addon-scopes=app to your mozconfig.

       Mark