add autocompletion for system names

UI/SystemSuggestionProvider.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections;
+using AutoCompleteTextBox.Editors;
+using NonaBGS.EDDB;
+
+namespace NonaBGS.UI {
+    public class SystemSuggestionProvider : ISuggestionProvider {
+        private PopulatedSystems systems = null;
+
+        public SystemSuggestionProvider(PopulatedSystems systems) {
+            this.systems = systems;
+        }
+
+        public PopulatedSystems Data {
+            get => systems;
+            set => systems = value;
+        }
+
+        public IEnumerable GetSuggestions(string filter) {
+            return systems.SystemNamesByFilter(filter);
+        }
+    }
+}