Add clockport connections

[tehKaiN]

http://www.ianstedman.co.uk/Amiga/designs/CDTV_Clockport/CDTV-Clockport.PNG

Default clockport address: D80000
Secondary clockport: D84000

But those are implemented by almost every CP expansion. 4-way expanders has also clockports on D88000 and D8C000 and those would be nice to have, since there'd limit collisions with internal expansions.

This can be implemented using 8-bit address decoder to decode D8 on uppest address byte and feeding A15 and A14 to demux for generating 4 CS signals. Exposing two clockport connectors with CSes assignable by jumpers should suffice.