Core/Scripts: return const modifier to Player methods back (should restore compilation for those with custom scripts).

NOTE: The main idea of original change is to allow scripts change content of message so that calling method sends modified message to client.
For example, moderating script which cuts illegal words from message.

--HG--
branch : trunk

src/server/game/Entities/Unit/Unit.cpp

@@ -5458,7 +5458,7 @@ bool Unit::HandleDummyAuraProc(Unit *pVictim, uint32 damage, AuraEffect* trigger
 
                     target = this;
                     if (roll_chance_i(10))
-                        this->ToPlayer()->Say(std::string("This is Madness!"), LANG_UNIVERSAL);
+                        this->ToPlayer()->Say("This is Madness!", LANG_UNIVERSAL); // TODO: It should be moved to database, shouldn't it?
                     break;
                 }
                 // Sunwell Exalted Caster Neck (??? neck)