Do not count `\r` as part of line width.
Do not count `\r` as part of line width.

Resolves #1335. Does not attempt to handle a `\r` not followed by a `\n` nor
attempt to handle Unicode intricacies (#6) including zero-width or multi-byte
characters.

aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,rust-lang/rustfmt,graydon/rust,SingingTree/rustfmt,rust-lang/rustfmt,SingingTree/rustfmt,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust