* Fix test usage of `which python`.
Also use `command -v` instead of `which` where needed.
* Fix testing_formatter.sh file checking.
The index is longer expected to exist when generating it.
The generation script is run with `set -eux`.
* Make script more portable
sha1sum is a Linux only command. Test for the command and if not found
use sha1 instead for portability. Avoid patches on BSD and Mac systems.
* Make the following scripts idempotent so that we only have to rebuild changed docs, not all docs:
* plugin_formatter
* generate_man
* dump_keywords.py
* dump_config.py
* testing_formatter.sh
