Remove the barrier waiting for FSM init. This COULD be a problem.
But currently its not possible anymore because of the design.
IF we need to this, one option is to have another callback from the engine. Or move FSM init out of do_sync_protocol().

remove the possibility to change SYNC/ASYNC handling of sync events at runtime.

It has to be defined at Session::initialize() and cannot be changed anymore. This is not needed.

a session CANNOT be refreshed.
The reason of the whole excercise it to guarantee that all sessions created will have the same callback functions registered on the engine (the ones from the CallbackDispatcher)

to be refactored into own modules.

should go into own module later

dont use the engine test folder.

No other session/thread will have sync callbacks registered.
This is essentially reverting a change that has been done for 3.0, but i think it was wrong

The C++ standards requires the order of init to be the order of declaration

macOS system sqlite.h changed and now the include guard token is _SQLITE3_H_ instead of SQLITE3_H as in the amalgamation. yay.

* test/Makefile (LDLIBS): Link libraries in a different order, respecting
dependencies.