[patch] PDO_FETCH_KEYS

Hi! I discovered that PDO::FETCH_KEY_PAIR does not work as documented. Documented is: 'Fetch into an array where the 1st column is a key and all subsequent columns are values' Actually, all but two column result sets throw an error... Then I thought about generalizing the fetch mode. Have 1..n 'key' columns. If only one value is left, assign it as a scalar. If multiple columns are left over, have it taken as FETCH_ASSOC. Please find attached a humble suggestion to generalize FETCH_KEY_PAIR to FETCH_KEYS, including an attribute to define the number of 'key' columns (defaults to one). The result should be fully backwards compatible. Please give me your suggestions. HPO PS: My diff includes my 'old' FETCH_2D patch.