Refactor various method names to more precisely reflect
what happens
Introduce CachingOmemoStore, SignalCachingOmemoStore,
which can be either used standalone as ephemeral OmemoStore
implementations, or as wrappers around other implementations
to add a cache layer for reduced storage access.
Get rid of "isFreshInstallation". Keys are now - given
that they don't exist - generated on startup.
Bump libsignal-protocol-java to 2.6.2
Prevent offline access to some functions which require
authenticated connection
Create more advanced unit tests and integration tests
Add async initialization function for OmemoManager
Remove session handling from smack-omemo.
This is now handled - in case of smack-omemo-signal -
solely by libsignal-protocol-java
Paul Schaub