Tune man page syntax.

Replace .Cm with .Ic; it seems more appropriate.
Use parentheses [open] quote macros (.Pq and .Po/.Pc) where the parentheses
contain other macros.
Update .Dd date.

(cherry picked from commit 5872c5384c28bb37ab1a62333cefa713525ff5cb)
Fix some formatting regressions after the latest kc.1 update.

(cherry picked from commit 347d611eab7f27c2a06e342159c051d126b991cf)