add warning for 2D conformations flagged as 3D (#2273)
add warning for 2D conformations flagged as 3D (#2273)


rdkit/rdkit,greglandrum/rdkit,ptosco/rdkit,ptosco/rdkit,bp-kelley/rdkit,rdkit/rdkit,bp-kelley/rdkit,rdkit/rdkit,greglandrum/rdkit,ptosco/rdkit,ptosco/rdkit,greglandrum/rdkit,greglandrum/rdkit,rdkit/rdkit,greglandrum/rdkit,greglandrum/rdkit,bp-kelley/rdkit,bp-kelley/rdkit,rdkit/rdkit,rdkit/rdkit,rdkit/rdkit,greglandrum/rdkit,ptosco/rdkit,bp-kelley/rdkit,ptosco/rdkit,bp-kelley/rdkit,greglandrum/rdkit,bp-kelley/rdkit,ptosco/rdkit,rdkit/rdkit,bp-kelley/rdkit,ptosco/rdkit