Improve namespacing

Revert to name.ml/name.mli (rm nameString.ml(|i))

Constructors suffixed with a single quote are names for elaborated programs
TODO: integrate them properly in elaboration,
particularly Name --> Name', LName --> LName'

Separate common labels (of ML records) from method names (lname)
Separate class names from type names (cname)

Gather functions working on names in module Name

Delete some .mle test files in inference/**