MolEnumerate should clear the reaction properties on its results

[greglandrum]

Describe the bug

In [11]: m = Chem.MolFromSmiles('COC |LN:1:1.3|')

In [12]: bndl = rdMolEnumerator.Enumerate(m)

In [13]: Chem.MolToCXSmiles(bndl.GetMol(0))
Out[13]: 'COC |atomProp:0.old_mapno.101:0.react_atom_idx.0:0.was_dummy.1:1.old_mapno.100:1.react_atom_idx.1:1.was_dummy.1:2.old_mapno.102:2.react_atom_idx.2:2.was_dummy.1|'

Those atom properties shouldn't be there.

Configuration (please complete the following information):

• RDKit version: master and release
• OS: all