List refactor (#179)

* Catch paginator bug if widget is disposed before request returns

* Refactoring paginated query widget

- Add option to enable / disable search filters

* Major refactor of paginated search widget

- Learned something new.. a state can access widget.<attribute>
- THIS CHANGES EVERTHING

* Preferences: Add code for tri-state values

- Also improve unit testing for preferences code

* Allow boolean form fields to be optionally tristate

* paginator: Allow custom boolean filters

* Remove outdated filtering preferences

* Refactor filter options

- Allow specification of more detailed options

* Add custom filters for "part" list

* filter tweaks

* Remove legacy "SublocationList" widget

* Add filtering option for locationlist

* Updates for stock location widget

* Refactor category display widget

* More widget refactoring

* Update main search widget

* Fix unit tests

* Improve filtering on BOM display page

lib/inventree/part.dart

@@ -32,15 +32,6 @@ class InvenTreePartCategory extends InvenTreeModel {
     };
   }
 
-  @override
-  Map<String, String> defaultListFilters() {
-
-    return {
-      "active": "true",
-      "cascade": "false"
-    };
-  }
-
   String get pathstring => (jsondata["pathstring"] ?? "") as String;
 
   String get parentPathString {
@@ -171,8 +162,7 @@ class InvenTreePart extends InvenTreeModel {
   @override
   Map<String, String> defaultListFilters() {
     return {
-      "cascade": "false",
-      "active": "true",
+      "location_detail": "true",
     };
   }
 

lib/inventree/stock.dart

@@ -224,7 +224,6 @@ class InvenTreeStockItem extends InvenTreeModel {
       "part_detail": "true",
       "location_detail": "true",
       "supplier_detail": "true",
-      "cascade": "false",
       "in_stock": "true",
     };
   }