WOFF2 update

Folks,

I've completed a full editorial review of the WOFF2 spec [1] and made few changes and corrections along the way [2]. Most notable changes include the removal of the following two conformance cases (leftovers from the mandatory transform times):
class="conform ff" id="conform-mustTransformTables"
class="conform at" id="conform-mustUseTransform"
and the updates to the "Changes" section of the spec. Everything else is pretty minor but please review the changes and let me know if I missed anything.

Please review them before the WG call tomorrow.

Thank you,
Vlad

[1] http://dev.w3.org/webfonts/WOFF2/spec/
[2] http://dev.w3.org/cvsweb/webfonts/WOFF2/spec/Overview.html.diff?r1=1.72;r2=1.73;f=h