draft Thunderbird 3.1 schedule

[Dan Mosedale]

[Note that replies are being directed to the dev-apps-thunderbird list]

I've drafted a schedule for Thunderbird 3.1:

https://wiki.mozilla.org/Thunderbird:Thunderbird3.1

Some things to note:

* String and features freezes for this release are targeted at the end
of beta 1. If anyone expects to land a feature with > 20 or so strings,
please contact me (dmose) ASAP so that I can coordinate with
localization teams sooner rather than later.

* I've switched from the M1/M2-style milestone naming previously
proposed back to the alpha/beta style naming as a result of previous
discussion here. I think being more approachable from the outside has
higher value to the project than I had considered.

Thoughts/feedback? Do the dates proposed make sense? Do they collide
in any important ways with holidays observed by sizable numbers of
contributors?

Dan