Add custom feeds selector, rework search, simplify onboarding (#325)

* Get home screen's swipable pager working with the drawer

* Add tab bar to pager

* Implement popular & following views on home screen

* Visual tune-up

* Move the feed selector to the footer

* Fix to 'new posts' poll

* Add the view header as a feed item

* Use the native driver on the tabbar indicator to improve perf

* Reduce home polling to the currently active page; also reuse some code

* Add soft reset on tap selected in tab bar

* Remove explicit 'onboarding' flow

* Choose good stuff based on service

* Add foaf-based follow discovery

* Fall back to who to follow

* Fix backgrounds

* Switch to the off-spec goodstuff route

* 1.8

* Fix for dev & staging

* Swap the tab bar items and rename suggested to what's hot

* Go to whats-hot by default if you have no follows

* Implement pager and tabbar for desktop web

* Pin deps to make expo happy

* Add language filtering to goodstuff

src/state/models/me.ts

@@ -33,6 +33,7 @@ export class MeModel {
   clear() {
     this.mainFeed.clear()
     this.notifications.clear()
+    this.follows.clear()
     this.did = ''
     this.handle = ''
     this.displayName = ''