isom: Force using UTF-8 to the output filename on Windows.
Add lsmash_convert_ansi_to_utf8() for Windows environment.
importer: Implementation of stream buffers for handling of H.264 and VC-1 streams.
ALS importer: Use stream buffers.
H.264 importer: Fix POC deduplication when starting from invalid negative POC.
H.264 importer: Raise threshold to determine invalid negative POC.