Topotecan Recruiting Phase 1 Trials for Neuroblastomas / Renal Cell Adenocarcinoma / Non-rhabdomyosarcoma Soft Tissue Sarcomas / Retinoblastoma / Rhabdoid Tumors / Sarcoma, Osteogenic / Wilms' tumor / Clear Cell Sarcoma of Soft Tissue / Hepatoblastomas / Germ Cell Tumors / Rhabdomyosarcomas / Ewing's Sarcoma (ES) Treatment