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git-annex-6.20160318: doc/devblog/day_373__away.mdwn

Caught up with a few last things today, before I leave for 
[a week in Boston](http://joeyh.name/trips/2016/boston/).

Converted several places that ran git hash-object repeatedly to feed data
to a running process. This sped up git-annex add in direct mode and with
v6 unlocked files, by up to 2x.