[7117] Implement explicit recipe discovery abilities.

* Implement SPELL_EFFECT_CREATE_ITEM_2 (157). This alos let work many item creating spells.
* Add `skill_discovery_template`.`reqClass` for allow clas specific racipes storing in table.
* Make primary key for `skill_discovery_template` pair (spellId,reqSpell) that allow have duplicate recipes for different reqSpells.
* Implement SPELL_EFFECT_SCRIPT (77) cases for explicit recipe discovery spells with learn spell selected by `skill_discovery_template` data.
Note: as expected explicit recipe discovery abilities always return some spell while exist any not learned yet for player class.

src/shared/revision_nr.h

@@ -1,4 +1,4 @@
 #ifndef __REVISION_NR_H__
 #define __REVISION_NR_H__
- #define REVISION_NR "7116"
+ #define REVISION_NR "7117"
 #endif // __REVISION_NR_H__