DLL_THREAD_ATTACH/DLL_THREAD_DETACH notifications, call
DisableThreadLibraryCalls() in order to slightly improve performance
on thread creation/exiting.
- Add implementation for IGetFrame.
- Implemented loading and writing of AVIs.
- Add some more stubs for some API functions.
- Add resources to avifil32.dll.
- Implemented AVISaveOptionsFree.
- Declared IID_* as extern in avifil32.spec (avoids linker problem).