Run slamhound on self

With clojure.pprint/*print-right-margin* set to 80.
Do not truncate original file until after reconstruction

Fixes regression introduced in 3c058a0a42efe1fab12430a2cd55b3c220d7a5af
(preserve comment headers).
Avoid excessive tempfile creation

Use of .deleteOnExit with tempfiles is convenient and has no practical
downsides when running slamhound from the command line.

However, when used from a persistent REPL the number and size of
tempfiles can grow to a non-negligible quantity. For instance, many
Linux distributions use a ramdisk (tmpfs) for /tmp; running slamhound on
a large file repeatedly can quickly consume megabytes of RAM.