Refactor search widget (#578)

* Refactor search widget

* Cleanup

* Fix for unallocated stock count

* Fix race condition

- Only upate results which match the current search term
- Prevents issues with multiple "competing" queries

* Fix for stock quantity

* Fix icon credits

* Tweak app bar color

* Cleanup visual stylinh

lib/widget/part/part_detail.dart

@@ -703,12 +703,10 @@ class _PartDisplayState extends RefreshableState<PartDetailWidget> {
   @override
   List<Widget> getTabs(BuildContext context) {
     List<Widget> tabs = [
-      Center(
-        child: ListView(
-          children: ListTile.divideTiles(
-          context: context,
-          tiles: partTiles()
-          ).toList()
+      SingleChildScrollView(
+        physics: AlwaysScrollableScrollPhysics(),
+        child: Column(
+          children: partTiles(),
         )
       ),
       PaginatedStockItemList({"part": part.pk.toString()})