* Server: delegate mod management & config to ServerModConfiguration (rename it to ServerModManager)
* Use c++11 range based loops
* Add unittests + experimental/default mod as a test case to permit testing mod loading in future tests
* Attempt to add registration confirmation
Using SRP auth mechanism, if server sent AUTH_MECHANISM_FIRST_SRP that means the player isn't exist.
Also tell player about the server and chosen username.
Local game has localhost as IP address of the server.
Add RenderingEngine::draw_menu_scene() to draw GUI and clouds background.
aborted -> connection_aborted
* Rewrite information message text
Client::promptConfirmRegister() -> Client::promptConfirmRegistration()
