restrict Algorithm.name values for simple observations

[pdowler]

There are some defacto standard algorithm names in use (exposure) and a few others that could be restricted for use with simple observations only (simulation was the one that prompted allowing other names in the first place.

[pdowler]

This is feasible. To have the xml schema enforce it we would have to use an enum. Otherwise, a vocabulary could be created and code validation for simple observations would be necessary.

Probably more hassle than value.