Hydroxymethyl-Branched Piperidines from Hydroxymethyl-Branched Lactones: Synthesis and Biological Evaluation of 1,5-Dideoxy-2-C-Hydroxymethyl-1,5-Imino-D-Mannitol, 1,5-Dideoxy-2-C-Hydroxymethyl-1,5-Imino-L-Gulitol and 1,5-Dideoxy-2-C-Hydroxymethyl-1,5-Imino-D-Talitol