[kepler-dev] DDFSingleTokenCommuntator depends on SR

[Christopher Brooks]

DDFSingleTokenCommutator depends on sr.lib.SingleTokenCommutator.

This means that Kepler, which uses DDF, must also ship SR.

Personally, I'd like to see Kepler include the SR director.

However, this dependency DDF-SR is _really_ wrong, since it
means that we can't deploy a DDF only interpreted ptolemy system
without including SR.  In general, domains should be standalone.

I'm thinking of moving sr.lib.SingleTokenCommutator to
actor.lib and then adding some code that would indicate that the
actor is not safe for use within SDF.

_Christopher