v0.5.5

Fixes

• MP4 export no longer fails on sources with an odd width or height (for example 2270×281). H.264 needs even dimensions, so the frame is now rounded down to even, losing at most one row or column, instead of the conversion dying with "finished with errors" and an opaque 0xdfaba7bb exit code.
• If an odd-dimension failure ever gets through, the error dialog now explains it in plain English instead of showing a hex code.