Proper RTL support (#1154)

* Add RTL styles. Most of the work is done by the browser 💖

* Refactor getLanguage

* Additional fixes

* Mirror the mouse pointer icon

* Move the vertical scrollbar to the left on RTL

* Revert "Mirror the mouse pointer icon"

This reverts commit f69b132538038d231b1b1acc0d6f4a28c91130bb.

src/components/App.tsx

@@ -78,7 +78,7 @@ import { actions } from "../actions/register";
 
 import { ActionResult } from "../actions/types";
 import { getDefaultAppState } from "../appState";
-import { t, getLanguage } from "../i18n";
+import { t } from "../i18n";
 
 import {
   copyToAppClipboard,
@@ -197,7 +197,6 @@ export class App extends React.Component<any, AppState> {
             return !element.isDeleted;
           })}
           setElements={this.setElements}
-          language={getLanguage()}
           onRoomCreate={this.createRoom}
           onRoomDestroy={this.destroyRoom}
           onLockToggle={this.toggleLock}