New flash tool, needs to be ported to Windows.

+ [f]ast is gone, current mode will be autodetected
+ uses hands-free firmware update if supported by the bootrom (to be committed)
+ uses new bootrom safety features against accidental misflashes (to be committed)
+ supports S19 files with base address 0x0 or base address 0x100000
+ supports old bootroms which expect 0x0 and new bootroms which expect 0x100000 (to be committed)
+ new argument style: first argument is comma-separated (no spaces!) list of partition names, remaining arguments are file names
  os and fpga may be abbreviated, bootrom must be given in full
  Examples:   ./flasher os ../armsrc/obj/osimage.s19
              ./flasher bootrom,o,f ../bootrom/obj/bootrom.s19 ../armsrc/obj/osimage.s19 ../armsrc/obj/fpgaimage.s19