Synthesis and Reactions of 3-Methylthiazolo[3,2-a]benzimidazole-2-carboxylic Acid Hydrazide: Synthesis of Some New Pyrazole, 1,3-Thiazoline, 1,2,4-Triazole and 1,2,4-Triazolo[3,4-b]-1,3,4-thiadiazine Derivatives Pendant to Thiazolo[3,2-a]benzimidazole Moiety