update authors/contributors list

update authors/contributors list

these additions were made by scanning git log since the last major
update in commit 790580b2fc47bc20e613336cb937a120422a770c. in addition
to git-level commit authorship, "patch by" text in the commit message
was also scanned. this idiom was used in the past for patches that
underwent substantial edits when merging or where the author did not
provide a commit message. going forward, my intent is to use commit
authorship consistently for attribution.

as before my aim was adding everyone with either substantial code
contributions or a pattern of ongoing simple patch submission; any
omissions are unintentional.