tabs: add clearURL method, loading tabs clears previous qps

Navigatable has clearURL, which for Search clears "search" qp, and
invites clears "invite" qp. Tab interfaces optionally include
"contentObject: AsTab", and show/hide funcs are passed the contentObject
of the previously loaded tab if one is available, so that they can call
it's clearURL method. This means searches you typed for the accounts tab
won't pop up when switching to activity.

ts/modules/tabs.ts

@@ -1,4 +1,4 @@
-import { PageManager } from "../modules/pages.js";
+import { PageManager } from "./pages";
 
 export function isPageEventBindable(object: any): object is PageEventBindable {
     return "bindPageEvents" in object;
@@ -12,7 +12,7 @@ export class TabManager implements TabManager {
     private _current: string = "";
     private _baseOffset = -1;
     tabs: Map<string, Tab>;
-    pages: PageManager;
+    pages: Pages;
 
     constructor() {
         this.tabs = new Map<string, Tab>();
@@ -26,14 +26,16 @@ export class TabManager implements TabManager {
     addTab = (
         tabID: string,
         url: string,
-        preFunc = () => void {},
-        postFunc = () => void {},
+        contentObject: AsTab | null,
+        preFunc: (previous?: AsTab) => void = (_?: AsTab) => void {},
+        postFunc: (previous?: AsTab) => void = (_?: AsTab) => void {},
         unloadFunc = () => void {},
     ) => {
         let tab: Tab = {
             page: null,
             tabEl: document.getElementById("tab-" + tabID) as HTMLDivElement,
             buttonEl: document.getElementById("button-tab-" + tabID) as HTMLButtonElement,
+            contentObject: contentObject,
             preFunc: preFunc,
             postFunc: postFunc,
         };
@@ -91,14 +93,16 @@ export class TabManager implements TabManager {
             [t] = this.tabs.values();
         }
 
+        const prev = this.tabs.get(this.current);
+
         this._current = t.page.name;
 
         if (t.preFunc && !noRun) {
-            t.preFunc();
+            t.preFunc(prev?.contentObject);
         }
         this.pages.load(tabID);
         if (t.postFunc && !noRun) {
-            t.postFunc();
+            t.postFunc(prev?.contentObject);
         }
     };
 }