allow for user-defined tiers for a Segment, like Praat?

[NickleDave]

Praat allows for multiple user-defined tiers per segment, e.g. "phoneme", "syllable", "word", "sentence".

http://www.fon.hum.uva.nl/praat/manual/Intro_7__Annotation.html

Not sure if that would be easy to add for Crowsetta.
I was thinking it would require the ability to dynamically add attributes to the Segment class, but I guess there could be an optional tiers attribute that's a dict mapping an annotation to each tier for any instance of a Segment.
But even then seq2csv would have to be able to handle mapping these extra tiers. I guess that's not too painful though if we're iterating over Segments anyway. Just would have to make sure all Segments have the same tiers.

[NickleDave]

Leaving this open but not assigning a milestone for now

Need to think about it more but being able to specify some ranked tiers seems like a "nice-to-have"

[NickleDave]

Actually this duplicates #42 so I'm closing this one after just referencing it in #170