Made pitch() and roll() angular, added surge() and sway()

Ryan,

I took your comments to heart and made pitch() and roll() angular, and added surge() and sway() for linear acceleration on X and Y.  Used a single-axis asin() solution, but in testing, it seems to do pretty well up to perpendicular on each axis. With the function in place, we could always add a two-axis solution later.

Enjoy.
Tom