zx128: link and crt0

zx128: link and crt0

Call the microdrive init functions
Do the initializer copy (makes no odds if disk loading, matters if ROM)
Shuffle things so that the kernel is at 0x0000->0x3FFF and 0xC000+. The
common, video and other bits then live between 5B and 9F. That leaves us
with A0-BF free plus the C0-FF of the other banks, so we can run somewhat
bigger apps. Not ideal but SDCC hacking is going to be needed to do better
plus teach fuse to emulate banked cartridges.

Memory map open to discussion anyway.

BUG: right now the mdv loader doesn't load 0xFE00-0xFFFF but needs to, need
to move the boot stack first.