Update to version 2.4.5

Changelog:
Fix for undo after downsampling video (regression).
Fix regression in resizing when encoding.
Fix missing audio issue after loading new audio for a clip.
Set default encoder to multi_encoder3 if python version >= 3.
Fix some message translation issues in dialog windows.
mplayer2 compatibility fix for ffmpeg_encoder.
Correct encoding framerate for mjpegtools_encoder dvd-ntsc format.
Minor fix for compiling without OSC.
Remove support for transcode_encoder.