fix the sense of the blame aspects of the blame object has a #:important

closes PR 13692
add an "contract on:" line for the case when an #:important argument
overrides the name of the value so we can keep that original name somewhere

related to PR 13692
add one more leading space to contract error messages (covering the first field)
change promise/c docs to use defproc instead of defform

also fix a few "listof/c"s

closes PR 13694