Changes to use common DirectorException class

Add director.swg for Go as was completely absent.
This is just the start of a common exception handling approach to directors.
An exception thrown in a Java director method will be propogated back to
Java via a C++ DirectorException.
DirectorException throws typemap for Java is fully working, all other languages need work.
DirectorException throws typemap for Perl added just to fix compilation errors.
Add director_exception_catches test.

Examples/test-suite/java/director_exception_catches_runme.java

@@ -0,0 +1,35 @@
+
+import director_exception_catches.*;
+
+public class director_exception_catches_runme {
+
+  static {
+    try {
+      System.loadLibrary("director_exception_catches");
+    } catch (UnsatisfiedLinkError e) {
+      System.err.println("Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.\n" + e);
+      System.exit(1);
+    }
+  }
+
+  public static void main(String argv[]) {
+
+    BaseClass b = new director_exception_catches_MyClass();
+
+    try {
+      String s = BaseClass.call_description(b);
+      throw new RuntimeException("Failed to catch exception");
+    } catch (NullPointerException e) {
+      if (!e.getMessage().startsWith("Testing exception thrown in BaseClass.description"))
+        throw new RuntimeException("Unexpected exception message: " + e.getMessage());
+    }
+  }
+}
+
+class director_exception_catches_MyClass extends BaseClass {
+  @Override
+  public String description() {
+    throw new NullPointerException("Testing exception thrown in BaseClass.description");
+  }
+}
+