Make the cursor next method return 1 if a row was available and 0 if …

…the cursor is exhausted, rather than generating a Tcl error if the cursor was exhausted. Previously the next method didn't return anything. Update README.md accordingly.

BUGZID:

README.md

@@ -267,7 +267,9 @@ Initialize or reinitialize a cursor.
 
 * $cursor next
 
-Move the cursor to the next row.
+Move the cursor to the next row.  Returns true if there is a next row, false if the cursor is exhausted.  
+
+Any error condition (CURSOR_INVALID, CURSOR_PENDING, CURSOR_QUERY_FAIL, CURSOR_BSON_ERROR), it generates a Tcl error and sets the error code to a list consisting of MONGO and the aforementioned condition code.
 
 * $cursor to_list
 

generic/cursor.c

@@ -345,8 +345,14 @@ mongotcl_cursorObjectObjCmd(ClientData cData, Tcl_Interp *interp, int objc, Tcl_
 		}
 
 		case OPT_CURSOR_NEXT: {
-			if (mongo_cursor_next (mc->cursor) != MONGO_OK) {
-				return mongotcl_setCursorError (interp, mc->cursor);
+			if (mongo_cursor_next (mc->cursor) == MONGO_OK) {
+				Tcl_SetObjResult (interp, Tcl_NewBooleanObj (1));
+			} else {
+				if (mc->cursor->err == MONGO_CURSOR_EXHAUSTED) {
+					Tcl_SetObjResult (interp, Tcl_NewBooleanObj (0));
+				} else {
+					return mongotcl_setCursorError (interp, mc->cursor);
+				}
 			}
 			break;
 		}