Remove unused 'Kitten.Type.Test' constructor

'Test' was unused; all references were merely pattern
matching and performing some default.
Travis CI integration
Bump minimum GHC version.
Add build status icon.
WIP Track origins of types for better error reporting

'Origin' now replaces 'Location' in the constructors of
'Type a'.

TODO

* Deduplicate type hints of nested types ('[Char (input to
  baq)] (input to baq)').

* Type hints for builtins (especially 'if', etc. and '@').

* type-error-3 is slightly confusing ('x's type is 'Char'???).

* Unit tests?