consistent local names

[wanderer]

It would be nice to have consistent local names across the wasm files

[axic]

• [x] any opcode mapping to an EEI method should use the parameters names from EEI
• [x] iszero* should have parameter names (and not just local indexes)
• [ ] arithmethics should stick to a0, a1, a2, a4, b1, b2, b3, b4
• [ ] mul_256 should have a description