lib: introduce export macros and hide all private symbols

lib/wp/module.h

@@ -14,14 +14,20 @@
 G_BEGIN_DECLS
 
 #define WP_TYPE_MODULE (wp_module_get_type ())
+WP_API
 G_DECLARE_FINAL_TYPE (WpModule, wp_module, WP, MODULE, GObject)
 
+WP_API
 WpModule * wp_module_load (WpCore * core, const gchar * abi,
     const gchar * module_name, GVariant * args, GError ** error);
 
+WP_API
 GVariant * wp_module_get_properties (WpModule * module);
+
+WP_API
 WpCore * wp_module_get_core (WpModule * self);
 
+WP_API
 void wp_module_set_destroy_callback (WpModule * module, GDestroyNotify callback,
     gpointer data);