ImgMath: add static methods to wrap a Number and a RandomAccessibleInterval.

Useful for e.g. copying an image into another, or filling an image with a number:

compute(img(source)).into(target)
compute(number(255)).into(target)

Author: acardona

src/main/java/net/imglib2/algorithm/math/ImgMath.java

@@ -232,4 +232,14 @@ static public final Else ELSE( final Object o )
 	{
 		return new Else( o );
 	}
+	
+	static public final < T extends RealType< T > > ImgSource< T > img( final RandomAccessibleInterval< T > rai )
+	{
+		return new ImgSource< T >( rai );
+	}
+	
+	static public final NumberSource number( final Number number )
+	{
+		return new NumberSource( number );
+	}
 }