add cancel button for new chat / new contact controller

deltachat-ios/NewContactController.swift

@@ -12,6 +12,7 @@ class NewContactController: UITableViewController {
     let nameCell = TextFieldCell.makeNameCell()
     let emailCell = TextFieldCell.makeEmailCell()
     var doneButton:UIBarButtonItem?
+    var cancelButton:UIBarButtonItem?
     
     var model:(name:String, email:String) = ("", "") {
         didSet {
@@ -33,6 +34,9 @@ class NewContactController: UITableViewController {
         doneButton?.isEnabled = false
         navigationItem.rightBarButtonItem = doneButton
         
+        cancelButton = UIBarButtonItem(barButtonSystemItem: .cancel, target: self, action: #selector(NewContactController.cancelButtonPressed))
+        navigationItem.leftBarButtonItem = cancelButton
+        
         nameCell.textField.addTarget(self, action: #selector(NewContactController.nameTextChanged), for: UIControlEvents.editingChanged)
         emailCell.textField.addTarget(self, action: #selector(NewContactController.emailTextChanged), for: UIControlEvents.editingChanged)
     }
@@ -56,6 +60,10 @@ class NewContactController: UITableViewController {
         }
     }
     
+    @objc func cancelButtonPressed() {
+        dismiss(animated: true, completion: nil)
+    }
+    
     required init?(coder aDecoder: NSCoder) {
         fatalError("init(coder:) has not been implemented")
     }