Core/DBLayer: make use of return result of Connection::Open method and allow core to output all the errors in prepared statements instead of aborting on first error.

src/server/shared/Database/MySQLConnection.h

@@ -121,10 +121,14 @@ class MySQLConnection
         MySQLPreparedStatement* GetPreparedStatement(uint32 index);
         void PrepareStatement(uint32 index, const char* sql, ConnectionFlags flags);
 
+        bool PrepareStatements();
+        virtual void DoPrepareStatements() = 0;
+
     protected:
         std::vector<MySQLPreparedStatement*> m_stmts;         //! PreparedStatements storage
         PreparedStatementMap                 m_queries;       //! Query storage
         bool                                 m_reconnecting;  //! Are we reconnecting?
+        bool                                 m_prepareError;  //! Was there any error while preparing statements?
 
     private:
         bool _HandleMySQLErrno(uint32 errNo);