Added list of plugins to config.
Restructured cli a little.
Added ext folder for plugins.
Removed ext folder.
Added cli plugin loading.

And removed server, as that became a test plugin.
Reduced some duplication.
Rewrote how the cli works to inject dependencies.

Also exposes the parts for the plugins - trust your plugins.
Removed markdown rendering.

The functionality can be implemented in a plugin.
Added Kasper to credits.
Merge branch 'master' into plugins

* master:
  Replaced GroupKey namedtuple with a class.
  Add build and dist folders to .gitignore
  Update requirements in setup.py to include jinja2
Rephrased comment.
Merge branch 'master' into exceptions

* master:
  Rephrased comment.
  Added Kasper to credits.
  Removed markdown rendering.
  Rewrote how the cli works to inject dependencies.
  Reduced some duplication.
  Added cli plugin loading.
  Removed ext folder.
  Added ext folder for plugins.
  Restructured cli a little.
  Added list of plugins to config.