*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

src/game/Chat.h

@@ -410,7 +410,7 @@ class TRINITY_DLL_SPEC ChatHandler
         bool HandleReloadSkillFishingBaseLevelCommand(const char* args);
         bool HandleReloadSpellRequiredCommand(const char* args);
         bool HandleReloadSpellAreaCommand(const char* args);
-        bool HandleReloadSpellElixirCommand(const char* args);
+        bool HandleReloadSpellGroupsCommand(const char* args);
         bool HandleReloadSpellLearnSpellCommand(const char* args);
         bool HandleReloadSpellLinkedSpellCommand(const char* args);
         bool HandleReloadSpellProcEventCommand(const char* args);