- don't delete the null logger.

- don't leak LogStreamInfo when detaching streams from DefaultLogger.
- detach the stream before deleting it in aiDetachAllLogStreams.
Thanks to Bart Botta for the patch.

- DefaultLogger does not properly delete log streams if they're still attached to it when the logger is destroyed. This is the behaviour specified in the documentation.
- Adapt AssimpView's logger usage, which didn't follow the spec as well.

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@659 67173fc5-114c-0410-ac8e-9d2fd5bffc1f

tools/assimp_view/MessageProc.cpp

@@ -2214,7 +2214,9 @@ int APIENTRY _tWinMain(HINSTANCE hInstance,
 
 	// initialise the default logger if neccessary
 	Assimp::DefaultLogger::create("",Assimp::Logger::VERBOSE);
-	Assimp::DefaultLogger::get()->attachStream((Assimp::LogStream*)&CLogWindow::Instance().pcStream,
+
+	CLogWindow::Instance().pcStream = new CMyLogStream();
+	Assimp::DefaultLogger::get()->attachStream(CLogWindow::Instance().pcStream,
 		Assimp::DefaultLogger::DEBUGGING | Assimp::DefaultLogger::INFO |
 		Assimp::DefaultLogger::ERR | Assimp::DefaultLogger::WARN);