Add Fractional Entrainment Rate (Tilde E; Peters et al. 2023) parameters

[AstroCGHA]

In Peters et al. (2023), Fractional Entrainment Rate ($\tilde{E}$) is the ratio between the Entraining CAPE and undiluted CAPE (either SB, MU, or ML parcel). It can discriminate between nonsupercell/ordinary TSTM and supercell TSTM, where the latter realize a larger percentage of their undiluted CAPE than nonsupercells.

I believe it can be added in the next version of SounderPy which can be something like this;

try:
thermo['sb_efrac'] = (thermo['sb_ecape'] / thermo['sbcape']) * 100.0
except:
thermo['sb_efrac'] = ma.masked
warnings.warn("SB-Entraining Fraction could not be computed for this sounding (calculation error)", Warning)
pass

try:
thermo['mu_efrac'] = (thermo['mu_ecape'] / thermo['mucape']) * 100.0
except:
thermo['mu_efrac'] = ma.masked
warnings.warn("MU-Entraining Fraction could not be computed for this sounding (calculation error)", Warning)
pass

try:
thermo['ml_efrac'] = (thermo['ml_ecape'] / thermo['mlcape']) * 100.0
except:
thermo['ml_efrac'] = ma.masked
warnings.warn("ML-Entraining Fraction could not be computed for this sounding (calculation error)", Warning)
pass

Parameters' unit are in percent.