Add channels for IBW tags

[akrherz]

Add custom channels for TOR/SVR warning IBW tags. This way a subscription could be made against a certain tag.

[akrherz]

Spit-balling some here...

Presently, the channels generated by the various parsers are used downstream has full text matches. Since the tags for wind, hail, and rainfall are scalar values, we'd need to consider how this could be used downstream. For example, one would want to subscribe to any hail tags >= 2 inches, so how can that be represented here?

Maybe we could use a [magnitude] within the tag value and thus add downstream logic for extracting that value and applying logic to it?

I don't think I have gotten any actual requests for this functionality, so pitch fork wielding users are not at the gates at the moment. It would be nice to come up with a solution.