- 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

code/Assimp.cpp

@@ -486,7 +486,9 @@ ASSIMP_API aiReturn aiDetachLogStream( const aiLogStream* stream)
 	if( it == gActiveLogStreams.end())	{
 		return AI_FAILURE;
 	}
+	DefaultLogger::get()->detatchStream( it->second );
 	delete it->second;
+
 	gActiveLogStreams.erase( it);
 
 	if (gActiveLogStreams.empty()) {
@@ -504,6 +506,7 @@ ASSIMP_API void aiDetachAllLogStreams(void)
 	boost::mutex::scoped_lock lock(gLogStreamMutex);
 #endif
 	for (LogStreamMap::iterator it = gActiveLogStreams.begin(); it != gActiveLogStreams.end(); ++it) {
+		DefaultLogger::get()->detatchStream( it->second );
 		delete it->second;
 	}
 	gActiveLogStreams.clear();