Structural chemistry of metal inorganic 3D MT frameworks. Templated nanoclusters–precursors Ga2(PO4)2F2 and Ga2(PO4)2(HF)F2 and self-assembly of crystalline gallophosphate structures (NH4)2[Ga2(PO4)2F2](KTP-Type) and (NH4)2[Ga2(PO4)2(HF)F2] (p-KTP-Type)