PATCHES: 48-hour notice for bar-extent and MMR key collision

[Graham Percival]

Unless I hear complaints (including a simple request for more time for
a particular item), these 3 patches will be pushed at 6pm on Tuesday,
1 Feb.

1)
remove bar-size and replace its usage by bar-extent
http://codereview.appspot.com/4025044/

2)
Fix 1120 in a way to avoid issues 1472, 1474
http://codereview.appspot.com/4095041/

3)
Fix 1472 ensure space for KeySignature
http://codereview.appspot.com/3994045/


Again, apologies if your particular patch isn't on this list.  We're
catching up on the patch backlog; please continue to be patient.

Cheers,
- Graham