Split NAME into upper/lower variants, remove Enum for now

I tried to split this apart, but after all the selective
hunk selection, git threw up an error, so blame git for
two things at once.
Change the parser to use initial lower for types/type constructors, initial cap for type vars
Change Option to option in the datashape language
Remove the Range type, it has no backing implementation anywhere
Remove Record as a type constructor, {} syntax is for records
Clean up the tests/errors for the lower/upper type/typevar distinction
Merge pull request #18 from mwiebe/typevar_uppercase

Typevar uppercase/type and type constructor lowercase