• Allow the ffmpeg_timeout arg in write_frames() to be None.
• Don't prevent sigint propagation for ffmpeg call in count_frames_and_secs().
• Removed a line in the part where read_frames() signals ffmpeg to quit, preventing "Invalid Argument" (Windows) and "Broken Pipe" (Linux) warnings. Previously we did not see these warnings because they were swallowed pre v0.4.0.
• More tests to avoid regressions.