undo/redo cleanup (#1165)

* fix refactoring error which disabled annotation file clearing

* fix undo behavior on add category label

* fix various undo/redo bugs

* remove logging

* further refinement of annotation undo/redo and actions

* address PR comment

client/src/components/categorical/categorical.js

@@ -24,7 +24,7 @@ class Categories extends React.Component {
     };
   }
 
-  handleCreateUserAnno = () => {
+  handleCreateUserAnno = e => {
     const { dispatch } = this.props;
     const { newCategoryText, categoryToDuplicate } = this.state;
     dispatch({
@@ -37,6 +37,7 @@ class Categories extends React.Component {
       categoryToDuplicate: null,
       newCategoryText: ""
     });
+    e.preventDefault();
   };
 
   handleEnableAnnoMode = () => {