updated Architecture. Make I/O mem mapped.

changed the formatting of the code a bit
reimplemented the opcode decoder.

Still lots to be done
changed JMP instruction. Use direct-immediate instead of offset operands

This is easier to implement both in the compiler and in hardware since no 16-bit addition has to be done
added a doc for the a binary counter used for the SP and PC.
fixed operand decoder table. Use binary counter chip for the SP and PC.

Lots of small changes.