Implemented more subtle connection handling.
Introduced new as sole constructor subroutine. Connect now is just used connect to the specified STOMP server.
Added CONNECTION_LOST event and implemented possibility for (un-)graceful disconnecting form the STOMP server.
Added support for virtual host specification in the connect_headers passed to the new subroutine.
Documented new subroutine and related changes.
Made disconnect subroutine croak similar to the connect subroutine.
Merge branch 'feature_#14-improve_connection_handling' into develop (closes #14).