Six- and Seven-Coordinate Manganese(II) Complexes of Schiff-Base Ligands Derived from the Condensation of 2,6-Diacetylpyridine with Ethanolamine (L1) or Propanolamine (L2); X-Ray Crystal Structures of (MnL1Cl2)·H2O and ((MnL2(NCS)2)x)