Macro commit

* Fixed Options for extra_params in UI
* Enhanced meta-programming for models
* Plugins can be imported from a python file if they're named
`senpy_<whatever>.py>` (no need for `.senpy` anymore!)
* Add docstings and tests to most plugins
* Read plugin description from the docstring
* Refactor code to get rid of unnecessary `.senpy`s
* Load models, plugins and utils into the main namespace (see __init__.py)
* Enhanced plugin development/experience with utils (easy_test, easy_serve)
* Fix bug in check_template that wouldn't check objects
* Make model defaults a private variable
* Add option to list loaded plugins in CLI
* Update docs

senpy/plugins/conversion/emotion/centroids.py

@@ -6,6 +6,11 @@ logger = logging.getLogger(__name__)
 
 
 class CentroidConversion(EmotionConversionPlugin):
+    '''
+    This plugin converts emotion annotations from a dimensional model to a
+    categorical one, and vice versa. The centroids used in the conversion
+    are configurable and appear in the semantic description of the plugin.
+    '''
     def __init__(self, info, *args, **kwargs):
         if 'centroids' not in info:
             raise Error('Centroid conversion plugins should provide '