*drop spell_elixir table

*add spell_group table for storage of groups of spell (kinda obvious, isn't it?) and populate the table with converted spell_elixir table data
*the table is going to be maintained by core team
*fix percentage display at spell_ranks table loading
*add TARGET_UNIT_CASTER to allowed learn spell targets in npc_trainer table, thanks to Aokromes for noticing the issue.

--HG--
branch : trunk

sql/updates/7280_world_command.sql

@@ -0,0 +1,2 @@
+DELETE FROM `command` WHERE `name` = 'reload spell_group';
+INSERT INTO `command` VALUES ('reload spell_group','3','Syntax: .reload spell_group\nReload spell_group table.');