Clean up verification and key cache a bit

resources/qml/UserProfile.qml

src/Cache.cpp

src/Cache.h

src/CacheCryptoStructs.h

src/Cache_p.h

src/ChatPage.cpp

src/ChatPage.h

src/DeviceVerificationFlow.cpp

src/DeviceVerificationFlow.h

src/timeline/.TimelineModel.cpp.swn

src/ui/UserProfile.cpp