add DO-VECTOR-DATA, remove special case from VECTOR-MAP-INTO
DO-VECTOR-DATA is like DOVECTOR, but uses WITH-ARRAY-DATA and grabs the
right reffer function so there's no per-element dispatch.
Since MAP used DOSEQUENCE for for-effect/arity-1 case, and DOSEQEUNCE in
turn uses DOVECTOR, replacing DOVECTOR there with DO-VECTOR-DATA we get the
a performance boost while being able to drop the special case in
Add a test for which the special case was broken: mapping a list into a