Lepidocrocite-Type Titanate Formation from Isostructural Prestructures under Hydrothermal Reactions: Observation by Synchrotron X-ray Total Scattering Analyses (Lepidocrocite-type Titanate Formation from Isostructural Prestructures under Hydrothermal Reactions: Observation by Synchrotron X-ray Total Scattering Analyses)