a remark about alternative universe handling
remove "merely" and mention "directedness" #317
clarify and index Fin(n), fix #294 and see #297
another example of a polymorphic function, close #297
fix #305
more comments on universes, fix #296
Merge pull request #319 from mikeshulman/fin

finite types and polymorphic functions
Merge pull request #320 from mikeshulman/fiberseq

fix #305
Merge pull request #317 from mikeshulman/universes

a remark about alternative universe handling