Create a Summon class and a summon_list to avoid using summon_db.

[jjppof]

Every time we need summon data, we access it directly from GoldenSun.dbs.summons_db. Even though it's working, would be nice to have a Summon class where its instances would be listed inside GoldenSun.info. In the future, when adding summons dynamically, this new Summon class will be helpful.