Increased accuracy of "degree" definition to avoid errors + updated Coulomb definition

The current definition of degree was rounded up, which made comparing Units::deg with CLHEP::deg problematic. I set the definition of the Units::deg to be equal to the CLHEP::deg to be able to compare them properly.

Also updated the definition of the Coulomb according to "Redefinition of SI, 20 May 2019" (https://www.bipm.org/utils/common/pdf/SI-statement.pdf) where they re-defined the Ampere, and thus redefined the Coulomb.