added vips::init() and vips::shutdown()

OS X mav was having trouble linking im_init_world() via the C++ API, so
we now have C++ functions for startup and shutdown.

ChangeLog

@@ -26,6 +26,7 @@
 - added --vips-profile, records and dumps thread timing and memory use info 
 - added vipsprofile, visualises --vips-profile output
 - auto-vectorization-friendly inner loops
+- added vips::init() and vips::shutdown() to C++ API
 
 20/11/13	started 7.36.5
 - better cache sizing in unbuffered sequential mode

libvipsCC/VImage.cc

@@ -52,6 +52,18 @@
 
 VIPS_NAMESPACE_START
 
+/* Useful to have these as C++ functions.
+ */
+bool init( const char *argv0 )
+{
+	return( vips_init( argv0 ) ); 
+}
+
+void shutdown( void )
+{
+	vips_shutdown(); 
+}
+
 void VImage::refblock::debug_print()
 {
 	std::list<refblock *>::iterator i;

libvipsCC/include/vips/VImage.h

@@ -60,6 +60,11 @@ extern "C" {
 
 VIPS_NAMESPACE_START
 
+/* vips_init() and vips_shutdown as namespaced C++ functions.
+ */
+bool init( const char *argv0 );
+void shutdown( void ); 
+
 /* A VIPS callback, our name for im_callback_fn.
  */
 typedef int (*VCallback)( void *, void * );