- [bug] Fixed more un-intuitivenesses in CTEs

  - [bug] Fixed more un-intuitivenesses in CTEs
    which prevented referring to a CTE in a union
    of itself without it being aliased.
    CTEs now render uniquely
    on name, rendering the outermost CTE of a given
    name only - all other references are rendered
    just as the name.   This even includes other
    CTE/SELECTs that refer to different versions
    of the same CTE object, such as a SELECT
    or a UNION ALL of that SELECT. We are
    somewhat loosening the usual link between object
    identity and lexical identity in this case.
    A true name conflict between two unrelated
    CTEs now raises an error.