ACTION-337: Update TTML2 publication timeline

Updated timeline circulated on 6th October 2014:

* Wednesday 8th Otober: 'last issues' closure date for TTML2 – any new
feature issues beyond this point to be deferred until after FPWD, e.g. to
CR or to v.next.
* Monday 27th and Tuesday 28th October (TPAC): substantive/contentious
issues on TTML2 to be discussed with proposals, and resolved with action
where necessary for implementation in FPWD or a subsequent WD.
* Week commencing 3rd November: publish TTML2 FPWD
* Thursday 20th November: all actions and issues on TTML2 due by the next
WD to be implemented; all others deferred to CR or v.next
* Tuesday 16th December: publish 'Last Call' style WD for wide review with
6 week review period (to allow for holiday season and time to get liaison
messages out notifying of the need for review).
* by Friday 19th December: internal and external liaison messages sent out
by Chair notifying of feature completeness and requesting review comments.
* Tuesday 17th January: WD wide review period ends
* After: process any review comments, request transition to CR – timeline
dependent on nature and volume of comments

Note that this doesn't actually alter our timelines significantly, or
possibly brings them forward by 2 days if you equate the 16th December WD
for wide review with the 17th December Last Call in the previous timeline.

It does allow for more time to generate the FPWD, and gives an opportunity
to publish a second WD incorporating any resolutions made during TPAC,
with some time to implement those resolutions.