Let script library know when some event is about to start. Event id's may be found in several sources, such as spells, GO's and transport/taxi paths.
Database scripts may be prevented by returning true from script side whenever needed. If false, DB script will run like normal.
New database table event_id_scripts will need a ScriptName for the event id, in same way as for example areatrigger_scripts.
Signed-off-by: NoFantasy <nofantasy@nf.no>
