Allow a Sud step to combine a ramp and a hold

A step can now carry both 'ramp' and 'hold': it ramps to the target
temp, then holds there for the given duration, instead of needing two
separate schedule entries. Sud.temp_reached() switches such a step
from its ramp phase into its hold phase in place (re-firing the
step-changed callback so SudTask/demo_sud re-apply the hold's stirrer
settings); user_wait_for_continue still applies once the whole step -
both phases - is done.

Merges sud_0010.json's three ramp/hold pairs into combined steps.

tasks/sud.py

@@ -37,8 +37,8 @@ class SudTask(ATask):
 		if hasattr(self.tc, 'set_model_params'):
 			self.tc.set_model_params(params['M'], params['C'])
 
-	def apply_stirrer(self, step):
-		stirrer_cfg = step.get('ramp', step.get('hold', {})).get('stirrer', {})
+	def apply_stirrer(self, phase):
+		stirrer_cfg = phase.get('stirrer', {})
 		speed = stirrer_cfg.get('speed', 0)
 		interval_time = stirrer_cfg.get('interval_time', 0)
 		on_ratio = stirrer_cfg.get('on_ratio', 1.0)
@@ -53,20 +53,28 @@ class SudTask(ATask):
 	def on_step_changed(self, step):
 		ramp = step.get('ramp') if step else None
 		hold = step.get('hold') if step else None
+		# A step may carry both 'ramp' and 'hold' (ramp to temp, then hold) -
+		# self.sud.state tells us which phase is currently active; it's
+		# already up to date by the time this callback fires, both on a
+		# full step transition and on the ramp->hold phase switch within
+		# one step (components/sud.py's temp_reached()).
+		ramping = self.sud.state == SudState.RAMPING
+		phase = ramp if ramping and ramp is not None else hold
+
 		if step is not None:
 			self.apply_plant_params(step)
-			if ramp is not None:
+			if ramping and ramp is not None:
 				self.tc.set_theta_soll(ramp['temp'])
 				self.tc.set_heatrate_soll(ramp['rate'])
-			self.apply_stirrer(step)
+			self.apply_stirrer(phase)
 
 		asyncio.create_task(self.send({'Step': {
 			'Index': self.sud.index,
-			'Type': 'ramp' if ramp is not None else 'hold' if hold is not None else None,
+			'Type': 'ramp' if ramping and ramp is not None else 'hold' if hold is not None else None,
 			'Descr': step.get('descr') if step else None,
 			'Temp': ramp.get('temp') if ramp else None,
 			'Rate': ramp.get('rate') if ramp else None,
-			'Duration': hold.get('duration') if hold else None,
+			'Duration': hold.get('duration') if (hold is not None and not ramping) else None,
 			'WaitForUser': step.get('user_wait_for_continue', False) if step else None,
 		}}))