CppTools: Fix qualified ids in the ':' locator filter

* Always display qualified ids in the ':' filter
* Show correct qualified ids (for some symbols the namespace was shown
  twice)

Task-number: QTCREATORBUG-10136

Change-Id: Id178cb4b8abcc316250fa16e5f3e5a8e72bc0c10
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
CppTools: Locator Tests: Make test data more descriptive

Change-Id: I23e88c8a04f82d51651038b38faf07057244fede
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
CppTools: Fix qualified ids in the symbol searcher

The leaves in the treeview contained qualified ids.

Change-Id: I290eaf9b1e666b6879d6d4b1f2483cfe7fb85362
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
C++: Stricter checking in TemplateNameId::Compare

Change-Id: I96dbce004d18147fd91485b1117dc65c4bbc08a0
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>