!per #3681 Performance and consistency improvements

- batch-write of persistent messages (user API)
- batch-write of events (in EventsourcedProcessor)
- command processing in EventsourcedProcessor by unstashing messages one-by-one from the internal stash
   * fixes performance issues that come up with unstashAll
- commands are not looped through journal actor but processed directly
- initial performance tests
  * command sourcing
  * event sourcing
  * event sourcing with user stash operations
- suppress stack traces in tests
=doc,osg Effort to get OSGi integration tests running again

* Update protobuf dependency so mvn clean install runs again
* Bump OSGi version range in AkkaBuild to include current 2.3 for generated manifests
* Update path in dev documentation to correct TexBasic folder