copyright and license

This code is under GPLv2.

Code made by Antoine Musso is under a joint copyright with the Wikimedia
Foundation since October 2012.

Change-Id: If1f645d01cce7df224839335bc4e9f06eef38dc9
slightly enhance inline documentation

Change-Id: I867ba436466f82fd381896e750dcef7f6950f95c