Minor bug fixes with help from Holiman.
FIX: sprint_hex, sprint_bin  has better length detection.
FIX: ui.c has removed all c99 array declarations, with malloc
FIX: hfmfmfu.c wrong length in one array caused crashes in CmdHF14AMfURdCard
FIX: cmdlft55xx.c CmdDump has now a correct pwd string.