Undo most of the namespace changes and use module again

Is a module like every other module, because if you import an empty
folder foobar it will be available as an object:
<module 'foobar' (namespace)>.

See #1033.

jedi/api/classes.py

@@ -153,13 +153,13 @@ class BaseDefinition(object):
         """The path to a module/class/function definition."""
         def to_reverse():
             name = self._name
-            if name.api_type in ('module', 'namespace'):
+            if name.api_type == 'module':
                 try:
                     name = list(name.infer())[0].name
                 except IndexError:
                     pass
 
-            if name.api_type in ('module', 'namespace'):
+            if name.api_type in 'module':
                 module_contexts = name.infer()
                 if module_contexts:
                     module_context, = module_contexts
@@ -521,7 +521,7 @@ class Definition(BaseDefinition):
         """
         typ = self.type
         tree_name = self._name.tree_name
-        if typ in ('function', 'class', 'module', 'instance', 'namespace') or tree_name is None:
+        if typ in ('function', 'class', 'module', 'instance') or tree_name is None:
             if typ == 'function':
                 # For the description we want a short and a pythonic way.
                 typ = 'def'

jedi/evaluate/context/namespace.py

@@ -4,7 +4,7 @@ from itertools import chain
 from jedi.evaluate.cache import evaluator_method_cache
 from jedi.evaluate import imports
 from jedi.evaluate.filters import DictFilter, AbstractNameDefinition
-from jedi.evaluate.base_context import NO_CONTEXTS, TreeContext
+from jedi.evaluate.base_context import TreeContext, ContextSet
 
 
 class ImplicitNSName(AbstractNameDefinition):
@@ -17,7 +17,7 @@ class ImplicitNSName(AbstractNameDefinition):
         self.string_name = string_name
 
     def infer(self):
-        return NO_CONTEXTS
+        return ContextSet(self.parent_context)
 
     def get_root_context(self):
         return self.parent_context
@@ -27,7 +27,10 @@ class ImplicitNamespaceContext(TreeContext):
     """
     Provides support for implicit namespace packages
     """
-    api_type = u'namespace'
+    # Is a module like every other module, because if you import an empty
+    # folder foobar it will be available as an object:
+    # <module 'foobar' (namespace)>.
+    api_type = u'module'
     parent_context = None
 
     def __init__(self, evaluator, fullname, paths):

jedi/evaluate/imports.py

@@ -419,7 +419,7 @@ class Importer(object):
 
             for context in self.follow():
                 # Non-modules are not completable.
-                if context.api_type not in ('namespace', 'module'):  # not a module
+                if context.api_type != 'module':  # not a module
                     continue
                 # namespace packages
                 if isinstance(context, ModuleContext) and context.py__file__().endswith('__init__.py'):