Uncharger not properly setting explicit/implicit H count

[greglandrum]

This is one that should have been merged before the release, but I forgot to create the issue an finish the PR. :-(

Here's the reproducible:

In [2]: from rdkit import Chem                                                                                                                                                  

In [3]: import rdkit                                                                                                                                                            

In [4]: rdkit.__version__                                                                                                                                                       
Out[4]: '2019.09.1'

In [6]: from rdkit.Chem.MolStandardize import rdMolStandardize                                                                                                                  

In [7]: uc = rdMolStandardize.Uncharger()                                                                                                                                       

In [9]: outm = uc.uncharge(Chem.MolFromSmiles('CC[NH-]'))                                                                                                                       
[15:53:00] Running Uncharger
[15:53:00] Removed negative charge.

In [10]: outm.Debug()                                                                                                                                                           
Atoms:
	0 6 C chg: 0  deg: 1 exp: 1 imp: 3 hyb: 4 arom?: 0 chi: 0
	1 6 C chg: 0  deg: 2 exp: 2 imp: 2 hyb: 4 arom?: 0 chi: 0
	2 7 N chg: 0  deg: 1 exp: 2 imp: 0 hyb: 4 arom?: 0 chi: 0
Bonds:
	0 0->1 order: 1 conj?: 0 aromatic?: 0
	1 1->2 order: 1 conj?: 0 aromatic?: 0

In [11]: print(Chem.MolToMolBlock(outm))                                                                                                                                        

     RDKit          2D

  3  2  0  0  0  0  0  0  0  0999 V2000
    0.0000    0.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
    1.2990    0.7500    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
    2.5981   -0.0000    0.0000 N   0  0  0  0  0  2  0  0  0  0  0  0
  1  2  1  0
  2  3  1  0
M  END

The explicit valence on the N should be 3 and there should be no valence flag set in the mol block.