MC truth using Double precision

MC truth values for Px, Py, Pz, E were given as float-precision before, this MR upgrades them to doubles. Floats were causing issues when trying to calculate energies for hammer, especially for electrons.

Shown below is what happens if you try to plot truth values of \sqrt{E^2 - p_x^2 - p_y^2 - p_z^2} for electrons as floating precision and double precision