Peter M. Groen / openbr

Allows specification of knn gallery name as a parameter

Have pipes attempt to flatten any child pipes they have

If we have e.g. an abbreviated algorithm, that will end up being its own pipe
even when this isn't neessarily desirable. By flattening in pipe::init, we
reduce the number of extraneous transforms in project, and Stream::init can
do a better job of reinterpreting as well.

Introduce a separate train method that models the inputs of separate project calls as separate list items

Clearly obtuse solutions to obtuse problems deserve top billing.

Current policy is to use TimeVaryingTransform::project since that is
thread-safe.

Rework SubjectTransform