New shebangs script; fixes to tar utilities and hugo-post script

The shebangs script helps me manage dependency listings.

The tar utilities were failing with to-directory options or passphrase
options containing space characters. The fix requires some unappealing
bash-isms, but at least it works.

hugo-post now will work from the root directory of a Hugo project.

Rewrote parts of untar, mktar,, tarcat, etc

Added --to-directory and --from-directory options throughout.

Added support for a variety of other archive file types.

Refactored archive logic

Almost all (un)archive code now lives in bash libraries. To add support
for a new compression or encryption algorithm, updates only need to be
made in `archive.bash`, `unarchive.bash`, and the parser in
`mktar-batch`.

`mktar-batch` has eclipsed `mktar` when it comes to explicit command
line options. Much of the logic wqas removed. `mktar` now soleyl exists
as a clever utility that guesses encryption/compression preferences
based on the output filename. Filename is now mandatory.

Refactored tests to reflect these changes.

Standardized use of here-strings in a couple of places.