Added missing 0xF9 opcode (ld sp, hl)

Added ticks count to ld a, a opcode
Fixed maths for ROM load
Updated fseek to use SEEK_* defines
Added PUSH and POP opcodes

Fixed small RRCA opcode bug (was doing the same as RRLA opcode)
Added some more LD missing opcodes

LD IO ports still missing
Added CALL and RET opcodes

Added a mising ADD opcode