textwrap-0.7.0
Version 0.7.0 changes the return type of Wrapper::wrap from Vec<String> to Vec<Cow<'a, str>>. This means that the output lines borrow data from the input string. This is a breaking API change if you relied on the exact return type of Wrapper::wrap. Callers of the textwrap::fill convenience function will see no breakage.
The above change and other optimizations makes version 0.7.0 roughly 15-30% faster than version 0.6.0.
The squeeze_whitespace option has been removed since it was complicating the above optimization. Let us know if this option is important for you so we can provide a work around.