• Added MiniMagick::Image#get_pixels, which returns a matrix where each member is a 3-element array of numbers between 0 and 255, one for each of the RGB channels.
• When MiniMagick.timeout is set and the command times out, previously the command would still continue running in the background. Now when Timeout::Error is raised, we also kill the subprocess running the command with SIGTERM.
• Implementation of posix-spawn has been improved, where now both stdout and stderr are read from at the same time, stdin pipe is closed immediately after writing the input, and stdout and stderr pipes are closed once the command finishes. This now has essentially the same behaivour as Open3.popen3 with a block.