-added new option, "force_cios_rev" (default 0 (=disabled)), if you
set it to for example "force_cios_rev=250", then wiiflow will
use IOS250 for the AUTO setting, for reload when using
"force_cios_load" and when switching to emu nand in IOS58 mode
-added more detailed debug prints and on screen information about
the currently loaded cIOS
-minor cleanup in nand get file and external booter