Fix:
* code completion
* follow symbols
* find usages

Task-number: QTCREATORBUG-8375
Change-Id: I6f35e809ba15f224c5a6d9b2fcfc18dbfba55411
Reviewed-by: Sergey Shambir <sergey.shambir.auto@gmail.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>