lsmashmuxer: Rename lsmashmuxer.auf into lwmuxer.auf.
lsmashdumper: Rename lsmashdumper.auf into lwdumper.auf.
lsmashinput: Rename lsmashinput.aui into lwinput.aui.
lwmuxer: Fix progress dialog.

This is a regression in 85e2b16a8a.
lwinput: Rename lsmashinput.h into lwinput.h.
lwlibav: Fix finding the first valid video frame when it will be output by feeding null packets.

This is a regression in 458cb1aa04.
lwinput: Display libav/ffmpeg library version and license.
AviUtl/configure: Add -lgdi32 to LIBS.
AviUtl: Add a README file.
AviUtl: Add a README for Japanese.
AviUtl/README: Move explanations around repeat flag into LW-Libav specific.
AviUtl/README: Tinker the documentation of Forward threshold slightly.
AviSynth: Add a README.
VapourSynth: Add a README.
README: Fix about demuxer of LW-Libav.
README: Correct the documentation of channel layout.
vslsmas: Support a compilation under Linux and OSX.

Cross-compilation is also possible.
lwlibav: Improve handling of PAFF field coded pictures.

Also fix seek around the last field coded pictures.
VapourSynth/configure: Fix DLL entry point on WIN32.

This is a regression in c7c519a9f6 .
lwlibav: Consider second field decoding for forward seek threshold.