Fix confidence comparisons

Now Handlers are correctly compared based on their confidence, so that
the one with the highest confidence is first to be retrieved from the
minheap.

kayleevc/kaylee.py

                 # Handle the command
                 handler(self.plugin_tts)
                 self._log_history(plugin, text)
+                break
             except queue.Empty:
                 break
                 # If an unknown error occurs, ignore it and keep trying

kayleevc/plugins/__init__.py

     """Base class for Kaylee plugin handlers
 
     Plugins should subclass this for their own command handlers.
+
+    Rich comparison methods are defined for use with queue.PriorityQueue.
+    They compare Handler objects based on their confidence alone, with
+    Handlers of high confidence comparing less than ones of low
+    confidence.
     """
 
     def __init__(self, confidence):
         When called, ``tts`` is a function which takes a string as its only
         parameter and passes it to Kaylee's configured text-to-speech system.
         """
+
+    def __eq__(self, other):
+        if isinstance(other, Handler):
+            return (self.confidence == other.confidence)
+        return NotImplemented
+
+    def __lt__(self, other):
+        if isinstance(other, Handler):
+            # Intentionally reversed
+            return (self.confidence > other.confidence)
+        return NotImplemented
+
+    def __le__(self, other):
+        if isinstance(other, Handler):
+            # Intentionally reversed
+            return (self.confidence >= other.confidence)
+        return NotImplemented
+
+    def __ge__(self, other):
+        if isinstance(other, Handler):
+            # Intentionally reversed
+            return (self.confidence <= other.confidence)
+        return NotImplemented
+
+    def __gt__(self, other):
+        if isinstance(other, Handler):
+            # Intentionally reversed
+            return (self.confidence < other.confidence)
+        return NotImplemented