Hi, thanks for the ChemPy package! As I was using Substance.from_formula, I noticed that one could easily make a mistake in the formula string and not be notified about it. For example, if I wanted to add methanol, if I don't make any mistakes it works great:

>>> from chempy import Substance
>>> methanol = Substance.from_formula('CH3OH')
>>> methanol.name
'CH3OH'
>>> methanol.composition
{6: 1, 1: 4, 8: 1}

If I make a minor mistake, for example forgetting to capitalize the first H for hydrogen, ChemPy gives no warning and simply stops at the last valid element. So the formula string is interpreted as simply C for carbon, even though the name is the entire supplied formula string Ch3OH:

>>> c = Substance.from_formula('Ch3OH')
>>> c.name
'Ch3OH'
>>> c.composition
{6: 1}

Is there something like a strict flag (option) to throw a warning or even exception (error) if the entire formula string cannot be interpreted as a substance? If the entire formula string cannot be interpreted as a substance, should the substance's name have only the part that was interpreted as a substance?