[z1990] Add support to call spell_scripts in more cases

* Support to script Dummy spells with spell_scripts
* Support to script TriggerSpell spells which have no existing triggered spell
Note that the order which spell-effect actually triggers the DB script is well-defined (SCRIPT_EFFECT before DUMMY before other)

Signed-off-by: Schmoozerd <schmoozerd@scriptdev2.com>

(based on commit bbd49f6)
(based on commit 804741c)

(cleaned version of fd4d16a)

(based on commit [s1578] - b880baa)