FeatureSimplePresence -> FeaturePresence in tests
ValidAccounts -> UsableAccounts in tests
SimplePresence -> Presence in tests
Client.Handler.HandleChannels -> HandleChannel in tests
Revert erronous prefixing of property name with TpDBus
Move from Client plural handler methods to singular in MyClient test

HandleChannels -> HandleChannel
ObserveChannels -> ObserveChannel
Some more ObserveChannels -> ObserveChannel
Move from Client plural handler methods to singular in another MyClient test
More TpEntityType -> TpHandleType in glib tests