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

tests/test_cli.py

@@ -12,7 +12,8 @@ class CLITest(TestCase):
     def test_basic(self):
         self.assertRaises(Error, partial(main_function, []))
 
-        res = main_function(['--input', 'test', '--algo', 'rand', '--with-parameters'])
+        res = main_function(['--input', 'test', '--algo', 'rand',
+                             '--with-parameters', '--default-plugins'])
         assert res.parameters['input'] == 'test'
         assert 'rand' in res.parameters['algorithm']
         assert res.parameters['input'] == 'test'