Fixed regression and fit algorithms and add sphere algorithm

The regression and fit no longer require the shower to go through (0, 0, 0).
(0, 0, 0) was a measurement, so it was often ok if the shower went through that point,
but it is more precise to allow it to deviate from that point, like it does from others.

The Sphere algorithm uses a different coordinate system than the rest, ECEF instead of ENU.
Also the timestamp is important and the result is in Equatorial instead of zenith azimuth coordinates.