Update conventions to use `No Op` instead of `Noop`

[OroArmor]

          looks like these are inconsistent, i prefer NO_OP over NOOP since i think it's more understandable if you haven't heard the phrase no-op before but i'd like to know what others think

Originally posted by @ix0rai in #621 (comment)

[Hex4dec]

I'd like it to be NOP but that's only because I like C and Assembly.