Inconsistency in the variable name for opcode

[AlessandroGrassi99]

In the processor logic, opcode is often called op_code or opcode. We have to decide which name to use definitely, in order not to confuse, not to have two variables doing the same thing, etc.

I propose opcode. It is easier to write and read. It also reflects the documentation better.

[guerinoni]

For me is the same, the meaning here is operation code, then since are 2 words is more consistent op_code, but no blocker from my side

[FedericoBruzzone]

I think the op_code is better then opcode for the same reason that @guerinoni said.