Automated fixes to follow Rust development

Hi,
    This is an automated pull request to help you follow recent Rust developments.
    Those changes were applied to spare you the tedious search and replace work needed.

    If you do not want to receive those kinds of pull requests, please say so and I'll ignore your repository.
    You can reach me here on Github, or on IRC (Freenode, Mozilla, etc) by the nickname 'geal'.

    Cheers!