[draft] implemented rom switch by IO_CONTROL, debug print now a switch

[mk2s]

We decided bit 7 of IO_CONTROL when 1 means "switch rom to bank" and the next bank we are switching to will be encoded in the lower bits(currently only bit 0) For now bits 6~1 are reserved.
We also decided IO_STATUS bit 6 means user rom is ready.
Added new fujinet-config.rom
Added feature to turn on/off debug from console at runtime:

help set fujinet_debug - to see the description of the setting
set fujinet_debug on - to enable it
set fujinet_debug off - to disable it
toggle fujinet_debug - to toggle between on/off

Matching config change is: FujiNetWIFI/fujinet-config#168
matching change in fujiversal: FozzTexx/fujiversal#1