- Fix Readme references & instructions
- node.py: fix covariances. Convert acceleration to m/s^2. Adapt to new arduino
output message YPRAG instead of YPRAMG
- update package.xml links to ahrs site
- Razor_AHRS.ino: upgrade Arduino package to 1.4.2 from Peter Bartz' site.
Fix link to his site. Document #ox output mode. Rename new mode #define
to better reflect what it does. Add #ox output mode back into Peter's
code.