fix in the Java binding: the Expr class should also ensure that libjpgf.so is loaded to avoid failures if Expr is the first class that is used.

src/runtime/java/org/grammaticalframework/pgf/Expr.java

@@ -54,4 +54,8 @@ public class Expr implements Serializable {
 			master = e.master;
 			ref    = e.ref;
 		}
+		
+		static { 
+			System.loadLibrary("jpgf");
+		}
 }