Remove outdated logging module (#966)

I haven't been through all of them yet, and some of those that I have
reviewed still have useful info that should be preserved. However, this
`logging.nu` version seems to long predate the one we now have in the
standard-library.

stdlib-candidate/std-rfc/logging.nu

@@ -1,6 +0,0 @@
-# This is a first attempt and some type of logging
-def log [message:any] {
-    let now = (date now | format date '%Y%m%d_%H%M%S.%f')
-    let mess = $"($now)|DBG|($message)(char nl)"
-    $mess
-}