Updates pull request from Roman Tsypuk to convert the build system from

ant to gradle.  Removes linux and windows application launch scripts and
produces an executable jar with all resources included.

src/main/java/io/github/dsheirer/audio/squelch/SquelchMode.java

@@ -0,0 +1,25 @@
+package io.github.dsheirer.audio.squelch;
+
+/**
+ * Squelch state for a decoding channel.  The state determines the handling of
+ * any audio packets processed by the channel state.
+ */
+public enum SquelchMode
+{
+	/**
+	 * Automatic: decoded message activity dictates squelch state and determines
+	 * if audio is passed
+	 */
+	AUTOMATIC,
+	
+	/**
+	 * Manually applied squelch noise level threshold determines if audio is
+	 * passed.
+	 */
+	MANUAL,
+	
+	/**
+	 * No Squelch - no squelch is applied and all audio is passed
+	 */
+	NONE;
+}