ew2ssam doesn't support SCNL

[alexander]

Per feedback from EW community forum, a barrier to wider (or, *current*) use of the module ew2ssam is the fact that it only supports SCN and not SCNL stream naming.

I'm setting the priority to 'major' only because of the level of effort that may be needed to fix the issue, not because it's a pressing need at this point (pending a decision regarding enhancements necessary to make use more attractive such as a different output format or additional consumers of the current output)