Deal with user specified INSTRUMENT_TYPE

[baconpaul]

We switch on INSTRUMENT_TYPE to set the internall wrapper handler. We actually only use this in one spot internally but we were failing to make a buildable wrapper if you set the type to something not in our list-of-three. So for now, warn and default out to internal instrument for the other types (which is probably the right behavior for aumf, which is what raised this issue in #271)

[defiantnerd]

yeah, thumbs up. it is build time, so that is a valid choice.

[djowel]

Thank you!