Fix GCC, Coverity and Krazy2 warnings

CMakeLists.txt

src/accountmodel.cpp

src/accountstatusmodel.h

src/bookmarkmodel.cpp

src/bookmarkmodel.h

src/call.cpp

src/callmodel.cpp

src/categorizedcompositenode.cpp

src/certificatemodel.h

src/ciphermodel.h

src/collectioneditor.cpp

src/collectioneditor.h

src/collectioneditor.hpp

src/collectioninterface.h

src/collectionmediator.h

src/collectionmediator.hpp

src/collectionmodel.cpp

src/contactmethod.cpp

src/contactproxymodel.cpp

src/contactproxymodel.h