When connecting pin, discard filter which is the same as the upstream
one.
Remove wrong extra IBaseFilter_Release.
Improve traces by showing filters owing pins we want to connect or
render.
Properly initialize output pin of transform filter.
AddRef pUnk in CopyMediaType.
Added CreateMediaType helper function and use it.
Replaced some DeleteMediaType calls to FreeMediaType to be in line
with recent changes.
Fixed IEnumMediaTypesImpl_Next.
Clear media type when initializing pins.
Added some AddRef/Release traces.
Jonathan Ernst