[Rock-dev] Future breakage in the GPS module

[Sylvain Joyeux]

The GPS module was outputting the position in ENU. The recent decision 
has been to use NWU (and "body X forward") as the Rock convention, 
mainly to match the ROS convention.

I'll push the change in the GPS module "soonish" (read: before the end 
of the week). I'll also push the necessary log migration script as soon 
as the infrastructure for it is decided.

Sylvain