- anonymous column expressions are automatically labeled.

  - anonymous column expressions are automatically labeled.
    e.g. select([x* 5]) produces "SELECT x * 5 AS anon_1".
    This allows the labelname to be present in the cursor.description
    which can then be appropriately matched to result-column processing
    rules. (we can't reliably use positional tracking for result-column
    matches since text() expressions may represent multiple columns).

  - operator overloading is now controlled by TypeEngine objects - the
    one built-in operator overload so far is String types overloading
    '+' to be the string concatenation operator.
    User-defined types can also define their own operator overloading
    by overriding the adapt_operator(self, op) method.

  - untyped bind parameters on the right side of a binary expression
    will be assigned the type of the left side of the operation, to better
    enable the appropriate bind parameter processing to take effect
    [ticket:819]