[sldev] Linden Lab Release Roadmap Update

[Joshua Bell]

Quick update:

* We're tentatively planning 1.19.0 releases for next week - server 
updates on Tuesday/Wednesday and hopefully a viewer RC0 on Thursday
* As predicted, doing the web-based authentication and work to stage the 
group chat changes over several releases took quite a while to get rock 
solid. We're finishing up QA on the whole shebang now.
* We're putting together the release notes (which is a project in 
itself) on this whole beastie - should be ready for sharing early next week.

There is very little distinction between the "release" development tip 
(soft just did a code drop for this) and the frozen 1.19.0 branch - the 
main difference is that we're putting bug fixes into the 1.19.0 branches 
to keep "release" stable. There are a handful of known UI issues as a 
result of some code refactoring; they're being tackled before RC0 goes 
live. (If there's a bug in both release and 1.19.0 that might seem 
backwards, but an as-yet-untested fix going into release could 
destabilize all development, whereas an if the bug is a ship-stopper, 
putting the as-yet-fix-untested into 1.19.0 doesn't make it any less 
shippable and lets us test it without blocking other developers.) We'll 
do a source drop of 1.19.0 and port the fixes to "release" and do 
another drop of that code as soon as we hit a good plateau.