Improve reference electrode module

[DunklesArchipel]

In #115 a reference electrode module was introduced to shift the potential scale of electrochemical data.

The following aspects require further attention.

• a generic Ag/AgCl electrode is included, since in some works the authors omit the concentration of the electrolyte. Values shift by ca. 30 mV between a saturated and low concentrated electrolyte. Possible this edge case should be included in the echemdb class in the method for reference scale conversion.
• temperature dependence should be included as methods, which return the value for a given temperature. warnings should be raised if temperatures are provided which are outside the range of the empirically determined reference values.
• unify electrode names such as Me/MeAnion-concentration-electrolyte. So far we mix abbreviations such as CE (calomel) and Hg/HgCl. The acronym could be implemented as an acronym.
• Include values for
  • MSE-sat
  • ADD MORE