added a test class for the Java API plus a small refinement in the implementation for the binding

src/runtime/java/Test.java

@@ -0,0 +1,8 @@
+import org.grammaticalframework.*;
+
+public class Test {
+	public static void main(String[] args) {
+		PGF gr = PGF.readPGF("/home/krasimir/www.grammaticalframework.org/treebanks/PennTreebank/ParseEngAbs.pgf");
+		gr.close();
+	}
+}