Auto populate 'Magnet Link' field with the address from clipboard

Co-authored-by: Jon Koops <jonkoops@gmail.com>

src/renderer/components/open-torrent-address-modal.js

@@ -1,8 +1,10 @@
 const React = require('react')
 const TextField = require('material-ui/TextField').default
+const { clipboard } = require('electron')
 
 const ModalOKCancel = require('./modal-ok-cancel')
 const { dispatch, dispatcher } = require('../lib/dispatcher')
+const { isMagnetLink } = require('../lib/torrent-player')
 
 module.exports = class OpenTorrentAddressModal extends React.Component {
   render () {
@@ -30,6 +32,12 @@ module.exports = class OpenTorrentAddressModal extends React.Component {
 
   componentDidMount () {
     this.torrentURL.input.focus()
+    const clipboardContent = clipboard.readText()
+
+    if (isMagnetLink(clipboardContent)) {
+      this.torrentURL.input.value = clipboardContent
+      this.torrentURL.input.select()
+    }
   }
 }