Make member searches work. Ref bug 1030312.

* "member" searches for a class no longer find the class: just its members. Hooray! (This is why some tests change.)
* "member" searches now find class-scoped typedefs. Hooray!
* Have compiler plugin emit qualnames for scopes. Remove scopelocs, which are no longer used.
* Switch to a qualified search in test_members so we don't find all the vars scoped to the constructor, which shares the name of the class.
* Remove variable unit test in favor of an integration test. member needles change this contract and invalidate the test.
* Remove dead process_override().
* Stop processing scopes into a special data structure. It wasn't necessary, and the code is simpler without it.
* Remove dead overrides_needles().