Use wrapt

[interrogator]

the wrapt module provides some helper decorators for making class decorators that attach to all methods. we do some creepy stuff to make this work, so it'd be better to rely on a well-known implementation.

[interrogator]

So last time we looked at this, we realised it's actually a bit hard to do, though it likely is the best way forward. I won't be even attempting this in the near future, but we can leave this open.

[hukkin]

Yeah I tried once (unfortunately didnt seem to push the code anywhere so can't find it now). Had an implementation but still had some of the tests failing. So yes, this might be harder than it sounds.