Added --plugins and --formats query support into osgconv to help with querying the

available plugins and the file formats/protocols they support

applications/osgconv/PluginQuery.cpp

@@ -39,3 +39,33 @@ FileNameList osgDB::listAllAvailablePlugins()
     
     return pluginFiles;
 }
+
+
+bool osgDB::queryPlugin(const std::string& fileName, ReaderWriterInfoList& infoList)
+{
+    if (osgDB::Registry::instance()->loadLibrary(fileName))
+    {
+        const Registry::ReaderWriterList& rwList = osgDB::Registry::instance()->getReaderWriterList();
+        for(Registry::ReaderWriterList::const_iterator itr = rwList.begin();
+            itr != rwList.end();
+            ++itr)
+        {
+            const ReaderWriter* rw = itr->get();
+            osg::ref_ptr<ReaderWriterInfo> rwi = new ReaderWriterInfo;
+            rwi->plugin = fileName;
+            rwi->description = rw->className();
+            rwi->protocols = rw->supportedProtocols();
+            rwi->extensions = rw->supportedExtensions();
+            rwi->options = rw->supportedOptions();
+            
+            infoList.push_back(rwi.get());
+        }
+
+        osgDB::Registry::instance()->closeLibrary(fileName);
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}