Set threshold on trigger setup default to 0.0 so it is typed as a float and not an int.

Author: Nick Clark

picoscope/picobase.py

@@ -464,7 +464,7 @@ def setExtTriggerRange(self, VRange=0.5):
 
         self._lowLevelSetExtTriggerRange(VRangeAPI["apivalue"])
 
-    def setSimpleTrigger(self, trigSrc, threshold_V=0, direction="Rising",
+    def setSimpleTrigger(self, trigSrc, threshold_V=0.0, direction="Rising",
                          delay=0, timeout_ms=100, enabled=True):
         """
         Set up a simple trigger.