Views: Column dictionaries now store and return pointers on column

pointers instead of column pointers.

src/obiview.h

@@ -119,7 +119,7 @@ typedef struct Obiview {
 	OBIDMS_column_p  columns[MAX_NB_OPENED_COLUMNS];    				/**< Array of pointers on all the columns of the view.
 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 */
 	hashtable_p		 column_dict;										/**< Hash table storing the pairs of column names or aliases with the associated
-																		 *   column pointers.
+																		 *   pointers on column pointers (OBIDMS_column_p*).
 																		 */
 	int				 nb_predicates;    									/**< Number of predicates to test when closing the view.
  	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 */