- CaseInsensitiveMap - keySet() now returns a case-insensitive set, and iterating that set returns originally stored string (no wrapper).
- Fixed up * imports
- keySet() now returns a Set that handles all possible Set APIs (view APIs which excludes add() and addAll()).
- keySet() and entrySet() returned from CaseInsensitiveMap() support all operations except for add() and addAll() (identical to how JDK provides view Set from these APIs).