Allow Start to restart a finished Sud from the beginning

start() only allowed a fresh run from IDLE, so once a brew reached
DONE, clicking Start again (the GUI correctly re-enables it once not
running) was silently a no-op. DONE now restarts the same way IDLE
does.

components/sud.py

@@ -140,13 +140,14 @@ class Sud(AttributeChange):
 		}
 
 	def start(self):
-		"""Starts a fresh run from IDLE, or resumes a paused one - whichever
-		applies. No-op otherwise."""
+		"""Starts a fresh run from IDLE or DONE (i.e. restarts from the
+		beginning once a previous run has finished), or resumes a paused
+		one - whichever applies. No-op otherwise."""
 		if self.state == SudState.PAUSED:
 			self.state = self._paused_from
 			self._paused_from = None
 			return
-		if self.state != SudState.IDLE:
+		if self.state not in (SudState.IDLE, SudState.DONE):
 			return
 		self.index = -1
 		self._advance()