Resolves #373 - Adds support for Tuner frequency error PPM monitoring

and auto-correction for R820T tuners.

-Updated TunerModel and TunerViewPanel to add 2 new columns to
display the current tuner's PPM setting and (when available) the
measured frequency error averaged over 5 second intervals provided by
certain decoders (e.g. P25 C4FM and LSM).  Frequency error value from
P25 decoders is provided from the Costas Loop PLL once 2 or more P25
message sync events have been observed in a short period.
-Updated R820T tuner to auto-correct PPM when measured frequency error
exceeds the +/- 0.4PPM threshold for a period of 30 seconds or more.
Feature can be enabled/disabled by user in the tuner editor panel.

Resolved several issues with P25 C4FM/LSM decoders that was impacting
performance related to channel misalignment from tuner PPM offsets.

src/main/java/io/github/dsheirer/dsp/symbol/ISyncDetectListener.java

@@ -15,7 +15,13 @@
  ******************************************************************************/
 package io.github.dsheirer.dsp.symbol;
 
+/**
+ * Listener interface to be notified each time a sync pattern has been detected and/or when the sync
+ * has been lost.
+ */
 public interface ISyncDetectListener
 {
-	void syncDetected();
+    void syncDetected();
+
+    void syncLost();
 }