Bug fix in Molecule::removeAtom
Bug fix in Molecule::removeAtom

Since m_formalCharges.size() is always equal to itself this line
would only work once and segfault when two calls to clearAtoms()
occurred in the same instance of Avogadro2.

Change-Id: I110ff44a4103c08f382d4af7f1d87cb25de99881

wadejong/avogadrolibs,ghutchis/avogadrolibs,OpenChemistry/avogadrolibs,ghutchis/avogadrolibs,OpenChemistry/avogadrolibs,wadejong/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,wadejong/avogadrolibs,ghutchis/avogadrolibs,ghutchis/avogadrolibs,ghutchis/avogadrolibs,wadejong/avogadrolibs