DEE Shield energy correction with new naming: correction, code rules applied

[vfioretti]

This pull request includes the comments of the pull request #101 , that is now closed.

In addition to:

• DEE Shield energy correction with DetectorID as string (e.g. X0).
• Standard error/warning/info handling with verbosity
• Minor bug correction in the shield energy correction class: if the new energy is below 0 is set to 0.
• New energy correction file in nuclearizer/resource/dee/ named ShieldEnergyCorrection_v2.csv

now the code rules are applied.
Corrections:

• if the simulated energy is negative (which should never happen but just in case), the code gives error
• if the FWHM is negative (which again shouldn't happen), the code applies the default noise. I used a gaussian noise with sigma = 10 keV as defined in the EM mass model.