1.0.28.48: fix regressions from 1.0.28.47

1.0.28.48: fix regressions from 1.0.28.47

  * Assert the declared element-type in the
    HAIRY-DATA-VECTOR-(REF|SET)/CHECK-BOUNDS transform, since
    HAIRY-DATA-VECTOR-(REF|SET) transforms no longer fire for
    non-simple arrays.

  * Turns out that %DATA-VECTOR-AND-INDEX was the only place where the
    index was checked being non-negative on some code paths -- not
    taking that route meant that type check weakening from INDEX to
    FIXNUM allowed negative indexes to slip in under the the radar in
    SAFETY 1 code.

    While this follows what we say in the manual, being more careful
    about bounds checks is probably a good idea, so be more
    conservative about weakenin integer types: collapse unions of
    intervals into a single interval, but dont' eliminate the most
    extreme bounds.

    Adjust one test that checked for the old behaviour, and
    update documentation.