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/common.mk

@@ -181,6 +181,7 @@ CPP_TEST_CASES += \
 	director_detect \
 	director_enum \
 	director_exception \
+	director_exception_catches \
 	director_extend \
 	director_finalizer \
 	director_frob \

Examples/test-suite/director_exception_catches.i

@@ -0,0 +1,25 @@
+%module(directors="1") director_exception_catches
+
+%include <std_string.i>
+%feature("director") BaseClass;
+
+%{
+// define dummy director exception classes to prevent spurious errors 
+// in target languages that do not support directors.
+
+#ifndef SWIG_DIRECTORS
+namespace Swig {
+  class DirectorException {};
+}
+#endif /* !SWIG_DIRECTORS */
+%}
+
+%catches(Swig::DirectorException) BaseClass::call_description;
+
+%inline %{
+struct BaseClass {
+  virtual std::string description() const = 0;
+  static std::string call_description(BaseClass& bc) { return bc.description(); }
+  virtual ~BaseClass() {}
+};
+%}

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");
+  }
+}
+