Transformations of Heterocyclic Amidines and Amide Oximes: Synthesis ofs-Triazolo[1′,5′:1,6]pyrimido[4,5-c]pyridazines,s-Triazolo[1′,5′:2,3]pyridazino[4,5-c]quinoline and 7H-2,3,4,6, 7-Pentaazabenz[d,e]anthracene, Derivatives of Novel Heterocyclic Systems