Move "Writing your own plugin" under Code components and layout, with the other
plugin docs.
Include instructions on how to install a plugin into a virtualenv and how to check
for its presence.
Document that users can install third-party plugins systemwide, but not with
certbot-auto.
Remove obsolete information from Authenticators section and make the section
more informative.
Remove IDisplay sub-section since it repeats information in the main "Plugin
architecture" section.
* remove instructions about removed Vagrantfile
* rewrite docker instructions
* say where docker-compose can be run
* give better intro for macOS devs
* prompt people for permission to install OS packages
* reword awkward sentence
* Change WORKDIR to /opt/certbot/src
This change is OK because all paths used in Dockerfile-dev are absolute paths.
* remove 'cd src' instructions for Dockerfile-dev
* Improve docker-compose testing instructions
Recommend faster-running commands with clearer output first, building up to
slow, noisy, `tox` last.
Remove outdated Boulder testing advice, and outdated Boulder testing scripts
(Vagrantfile, mac-bootstrap.sh, boulder-start.sh). Update Boulder testing
section.
Fill out "directory structure" section of contributing guide a little better.
They're now used only by the le-auto build process. The new public interface for OS-level bootstrapping is le-auto --os-packages-only, which dispatches by OS automatically. That obsoletes install-deps.sh as well, saving some repetition.
Also, switch to mustache-style templating to avoid colliding with shell variable references.
To optimize for the docker cache, we could later add a shim script that sources just deb_common.sh and calls its bootstrap function.
This makes the script more readable and easier to work on. We'll stitch it together with a build process.
Also, stop passing the sudo command as an arg to the experimental bootstrappers. They will be inlined into the main script and can just reference $SUDO. As a result, stop recommending devs run the scripts manually, instead running le-auto --os-packages-only. This has the nice side effect of making dev documentation simpler.
Name the folder "letsencrypt_auto" rather than "letsencrypt-auto" because git yield endless pain when replacing a file with a dir. Perhaps we can change it with impunity in a latter commit.
