Wire the Start toolbar action to actually start the Sud sequence

Sends {'Start': True} on the Sud channel, which SudTask.recv() already
maps to sud.start(). Only reachable while enabled (loaded and idle),
per update_sud_actions().

client/brewpi_gui.py

@@ -187,6 +187,7 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 		self.setupUi(self)
 		self.update_sud_actions()
 		self.btn_connect.clicked.connect(self.on_btn_connect_clicked)
+		self.actionStart.triggered.connect(self.on_action_sud_start)
 		self.actionSudDownload.triggered.connect(self.on_action_sud_download)
 		self.actionSudUpload.triggered.connect(self.on_action_sud_upload)
 		self.Slider_pwr_soll.valueChanged.connect(self.on_slider_pwr_soll_changed)
@@ -306,6 +307,9 @@ class Window(QtWidgets.QMainWindow, Ui_MainWindow):
 		print("on_checkbox_stirrer_activate_changed {}".format(value))
 		self.msg_stirrer.send({'Activate': int(value == 2)})
 
+	def on_action_sud_start(self):
+		self.msg_sud.send({'Start': True})
+
 	def on_action_sud_download(self):
 		# Pick the destination up front, on the GUI thread - the actual
 		# write happens in on_sud_changed(), which runs off a worker thread