[v9_11] Minor improvements to code handling managed keys 4812. [bug] Minor improvements to stability and consistency of code handling managed keys. [RT #46468] (cherry picked from commit 312c84c73aaffff6d13bb56eef688be68aea3392)

4634. [contrib] check5011.pl needs to handle optional space before semi-colon in +multi-line output. [RT #45352] (cherry picked from commit ed2659c9747d917a3cbec336790e7583056bc563)

[master] update contrib 3725. [contrib] Updated zkt and nslint to newest versions, cleaned up and rearranged the contrib directory, added a README.