New definition of but0 inconsistent with original definition

[kent0]

but0 was defined as the \int <gx,gy,gz> \cdot <ub,vb,wb> tb d\Omega
but now is defined with the direction theta with a unit vector

The new definition is redundant since a linear combination of but0_x and but0_y (without the gx,gy scaling) can be used in the online mode and the old definition can be restored.