[WIP] Adds locking mechanism to tuner controllers so that the

polyphase channel manager can block users from changing frequency and/or
sample rate when polyphase channels are allocated.

src/main/java/io/github/dsheirer/source/tuner/manager/TunerChannelSourceManager.java

@@ -433,6 +433,9 @@ public class TunerChannelSourceManager extends ChannelSourceManager
             case NOTIFICATION_CHANNEL_COUNT_CHANGE:
                 //Rebroadcast this event to any registered listeners (ie tuner and tuner controller)
                 broadcast(sourceEvent);
+                //Lock the frequency and sample rate controls on the tuner controller so users can't change them
+                //when the polyphase manager has channels allocated
+                mTunerController.setLocked(getTunerChannelCount() > 0);
                 break;
             default:
                 mLog.info("Unrecognized source event: " + sourceEvent);