Currently, Rust's standard library will yield an error if one tries to
write invalid UTF-8 to a Windows console. This is problematic for
ripgrep when it tries to print matched lines that contain invalid UTF-8.
We work around this by modifying the `termcolor` library to lossily
decode UTF-8 before sending it to `std::io::Stdout`. This may result in
some Unicode replacement chars being shown in the output, but this is
strictly better than erroring or not showing anything at all.
Fixes#318.
ed60ec736c