LPow correction

[VLD/VMB]

I can think of several solid mathematical reasons to define 0^0 as 1
and no reason not to.  It happens that there's no way to represent
an "indeterminate form" on our machines, so I have to choose something.
It might as well be the most generally useful choice.

I also think atan2(0.,0.) should be defined as 0. for computation.
I've never seen a case where this wasn't what I wanted.