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/dsp/symbol/Dibit.java

@@ -0,0 +1,112 @@
+package io.github.dsheirer.dsp.symbol;
+
+public enum Dibit
+{
+	D01_PLUS_3( false, true,  1, 4 ),
+	D00_PLUS_1( false, false, 0, 0 ),
+	D10_MINUS_1( true, false, 2, 8 ),
+	D11_MINUS_3( true, true,  3, 12 );
+	
+	private boolean mBit1;
+	private boolean mBit2;
+	private int mLowValue;
+	private int mHighValue;
+	
+	private Dibit( boolean bit1, boolean bit2, int lowValue, int highValue )
+	{
+		mBit1 = bit1;
+		mBit2 = bit2;
+		mLowValue = lowValue;
+		mHighValue = highValue;
+	}
+
+	/**
+	 * Allowable transition state 1 for trellis coded modulation.  Indicates 
+	 * the dibit that differs from this dibit in the LSB bit position.
+	 */
+	public Dibit getAllowableTransition1()
+	{
+		switch( this )
+		{
+			case D00_PLUS_1:
+				return D01_PLUS_3;
+			case D01_PLUS_3:
+				return D00_PLUS_1;
+			case D10_MINUS_1:
+				return D11_MINUS_3;
+			case D11_MINUS_3:
+				return D10_MINUS_1;
+			default:
+				/* We'll never get here */
+				return D00_PLUS_1;
+		}
+	}
+	
+	/**
+	 * Allowable transition state 2 for trellis coded modulation.  Indicates 
+	 * the dibit that differs from this dibit in the MSB bit position.
+	 */
+	public Dibit getAllowableTransition2()
+	{
+		switch( this )
+		{
+			case D00_PLUS_1:
+				return D10_MINUS_1;
+			case D01_PLUS_3:
+				return D11_MINUS_3;
+			case D10_MINUS_1:
+				return D00_PLUS_1;
+			case D11_MINUS_3:
+				return D01_PLUS_3;
+			default:
+				/* We'll never get here */
+				return D00_PLUS_1;
+		}
+	}
+
+	/**
+	 * Indicates if the trellis coded modulation dibit is allowed to transition 
+	 * to the dibit argument.  
+	 */
+	public boolean isAllowableTransition( Dibit dibit )
+	{
+		return dibit == getAllowableTransition1() ||
+			   dibit == getAllowableTransition2();
+	}
+	
+	public boolean getBit1()
+	{
+		return mBit1;
+	}
+	
+	public boolean getBit2()
+	{
+		return mBit2;
+	}
+	
+	public int getLowValue()
+	{
+		return mLowValue;
+	}
+	
+	public int getHighValue()
+	{
+		return mHighValue;
+	}
+	
+	public static Dibit inverted( Dibit symbol )
+	{
+		switch( symbol )
+		{
+			case D10_MINUS_1:
+				return D11_MINUS_3;
+			case D11_MINUS_3:
+				return D01_PLUS_3;
+			case D00_PLUS_1:
+				return D10_MINUS_1;
+			case D01_PLUS_3:
+			default:
+				return D00_PLUS_1;
+		}
+	}
+}