Round pre-heat temperature and duration to integer but allow floats

We want to allow floats in the interface since the interface needs to be agnostic of what device it is connected to. But the UM3 API only allows integers, so we still need to round it to the nearest integer.

Contributes to issue CURA-3161.

plugins/UM3NetworkPrinting/NetworkPrinterOutputDevice.py

@@ -247,8 +247,10 @@ class NetworkPrinterOutputDevice(PrinterOutputDevice):
     #   Celsius.
     #   \param duration How long the bed should stay warm, in seconds. Defaults
     #   to a quarter hour.
-    @pyqtSlot(int, int)
+    @pyqtSlot(float, float)
     def preheatBed(self, temperature, duration):
+        temperature = round(temperature) #The API doesn't allow floating point.
+        duration = round(duration)
         url = QUrl("http://" + self._address + self._api_prefix + "printer/bed/pre_heat")
         if duration > 0:
             data = """{"temperature": "%i", "timeout": "%i"}""" % (temperature, duration)