list: cleanup, include offset in DateAttempt

included UTC offset in minutes in DateAttempt, will be used shortly.
Also moved this stuff (ParsedDate, DateAttempt) to the common d.ts, and
the method for parsing from a string (now parseDateString) to common.
Also pre-emptively load the user cache when the admin page loads.

ts/modules/list.ts

@@ -4,6 +4,10 @@ import "@af-utils/scrollend-polyfill";
 
 declare var window: GlobalWindow;
 
+export interface ListItem {
+    asElement: () => HTMLElement;
+};
+
 export class RecordCounter {
     private _container: HTMLElement;
     private _totalRecords: HTMLElement;
@@ -342,7 +346,7 @@ export abstract class PaginatedList {
             this.lastPage = resp.last_page;
 
             appendFunc(resp);
-            
+           
             this._counter.loaded = this._search.ordering.length;
             
             if (post) post(resp);