more efficient import statement

src/viewer/ui/export.tsx

@@ -1,4 +1,4 @@
-import React = require('react');
+import * as React from 'react';
 import { CollapsableControls, CollapsableState, PluginUIComponent } from 'molstar/lib/mol-plugin-ui/base';
 import { Button } from 'molstar/lib/mol-plugin-ui/controls/common';
 import { GetAppSvg } from 'molstar/lib/mol-plugin-ui/controls/icons';