Merge window move

[Boudewijn Rempt]

We will move the opening of the merge window to Tuesday because there
are two issues that need to be fixed before we can make a release:

* The shift-drag slowdown bug
* A new deadlock following from 9c34fef3320983c8e0542363121

We will revert the latter commit, but time is needed to fix the first
bug.

Packages will be made Monday evening, and we will release on Tuesday.

-- 
Boudewijn Rempt | http://www.krita.org, http://www.valdyas.org