Changes to rebom and library

Rebom now acts like cat, just including a BOM in front.

The library has been updated to dump usage, version, and help messages
regardless of the quiet option (-q, --quiet). Previously, the observed
behavior depended on the order of options. Dumped messages were
processed at the time they were seen, so they would ignore a quiet
option that followed. It is better to behave consistently than to obey
the user inconsistently.

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.

Standardization of docs, [[ usage, local variables.

Added an archive helper function.

Moving gitstat into public repo

Fix unittest

Help text specified wrong option.

Formatting fixes; Help message fixes

Added core README; dropped one not-so-useful script

Refactored code into multiple 'packages'. One day these may be
independently installable. For now it's just an organization method.

Rewrote main README and added per-package READMEs.

Also: bug fix on whiched and whichvi. They formerly propogated an error
if $EDITOR or $VISUAL were set to a non-existant executable. Also
improved the inline documentation.