Qml app improved trusted nodes exchange

AddTrustedNode.qml support for plain certificate and node link import/export
Move clipboard wrapper to it's own singleton ClipboardWrapper.qml with
  improved clipboard API

retroshare-qml-app/src/ClipboardWrapper.qml

@@ -0,0 +1,47 @@
+/*
+ * RetroShare Android QML App
+ * Copyright (C) 2017  Gioacchino Mazzurco <gio@eigenlab.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+pragma Singleton
+
+import QtQml 2.2
+import QtQuick 2.7
+import QtQuick.Controls 2.0
+
+QtObject
+{
+	/// Public API
+	function postToClipBoard(str)
+	{
+		console.log("postToClipBoard(str)", str)
+		privTF.text = str
+		privTF.selectAll()
+		privTF.cut()
+	}
+
+	/// Public API
+	function getFromClipBoard()
+	{
+		privTF.text = "getFromClipBoard()" // Need some text for selectAll()
+		privTF.selectAll()
+		privTF.paste()
+		return privTF.text.toString()
+	}
+
+	/// Private
+	property TextInput privTF: TextInput { visible: false }
+}