Added subclass descriptions

dungeonsheets/features/features.py

@@ -83,3 +83,17 @@ class Feature():
         return -100
 
 
+class FeatureSelector(Feature):
+    """
+    A feature with multiple possible choices.
+    """
+    options = dict()
+
+    def __init__(self, selection=None):
+        keep_source = self.source
+        # Transform into selected feature
+        if selection.lower() in self.options():
+            new_feat = self.options[selection.lower()]
+            self.__dict__.update(new_feat.__dict__)
+            new_feat.__init__(self)
+        self.source = keep_source