Simple RECREATE_DATABASE is equal to CREATE_DATABASE,
RECREATE_DATABASE OVERWRITE is equal to REPLACE_DATABASE.
2. gbak uses isc_dpb_overwrite to create database over existing files
3. engine overwrite existing files only if asked explicitly by
user by setting isc_dpb_overwrite to 1
4. fixed unregistered bug - when gbak uses service manager and passed
command line contains invalid switch. Service reports error and
finish but not call Service::svc_started therefore response is not
send and gbak is stalled forever