Simplified ch16-02 transmitter cloning

[jalexvig]

No description provided.

[carols10cents]

This was purposeful, actually. Because mspc::Sender's implementation of Clone isn't actually doing a copy of data (it performs actions similar to increasing a reference count), this call to clone is inexpensive in comparison to most calls to clone. By choosing to call clone using expanded syntax, we can communicate to the reader of the code that this clone is not doing potentially-unnecessary allocations.

This is a fairly new Rust style, but one we've chosen to use throughout the book.

Thank you for the PR though!

[jalexvig]

Thanks for the intel Carol! Really appreciate the work you and Steve put into this book.