Propogate boolean in Headstage64 stimulator triggers

- These operators were not acting as sinks because they were not
  propogating their observable sequence
- Fixes #83

Author: jonnew

OpenEphys.Onix1/Headstage64ElectricalStimulatorTrigger.cs

@@ -208,7 +208,11 @@ public override IObservable<bool> Process(IObservable<bool> source)
                 {
                     var device = deviceInfo.GetDeviceContext(typeof(Headstage64ElectricalStimulator));
                     var triggerObserver = Observer.Create<bool>(
-                        value => device.WriteRegister(Headstage64ElectricalStimulator.TRIGGER, value ? 1u : 0u),
+                        value =>
+                        {
+                            device.WriteRegister(Headstage64ElectricalStimulator.TRIGGER, value ? 1u : 0u);
+                            observer.OnNext(value);
+                        },
                         observer.OnError,
                         observer.OnCompleted);
 

OpenEphys.Onix1/Headstage64OpticalStimulatorTrigger.cs

@@ -202,7 +202,11 @@ public override IObservable<bool> Process(IObservable<bool> source)
                 {
                     var device = deviceInfo.GetDeviceContext(typeof(Headstage64OpticalStimulator));
                     var triggerObserver = Observer.Create<bool>(
-                        value => device.WriteRegister(Headstage64OpticalStimulator.TRIGGER, value ? 1u : 0u),
+                        value =>
+                        {
+                            device.WriteRegister(Headstage64OpticalStimulator.TRIGGER, value ? 1u : 0u);
+                            observer.OnNext(value);
+                        },
                         observer.OnError,
                         observer.OnCompleted);