Returns a context containing a logger that forks all of its output to both the parent context's logger and to the given `io.Writer`.

DefaultEnv returns a set of strings in the form of "key=value" based on the current process' environment with additional entries to improve subprocess log output.

PrepareEnv returns a set of strings in the form of "key=value" based on a provided set of strings in the same format with additional entries to improve subprocess log output.

Most progress lines are optional.

A logger that buffers its log lines until we have an output logger.

Logger with better controls for levels and colors.

Allow arbitrary fields on a log.