Do not rename packages on `cargo new`.
Do not rename packages on `cargo new`.

Prior to this commit, packages beginning with `rust` or ending with
`rs` were renamed automatically when created, unless they were
binaries. The ostensible purpose of this code was to avoid people
uploading "redundant" names to crates.io, which is a repository of
Rust packages.

This behavior was overly opinionated. It is not cargo's
responsibility to discourage users from naming their packages any
particular way. Without a sound technical reasons why packages
cannot be named a certain way, cargo should not be intervening in
users' package naming decisions.

It also did this by automatically renaming the package for the
user, as opposed to erroring. Though it printed a message about
the behavior, it did not give the user a choice to abort the
process; to overrule cargo they had to delete the new project
and start again using the `--name` argument.

`cargo new` is many users' first entrypoint to the Rust ecosystem.
This behavior teaches a user that Rust is opinionated and magical,
both of which are divisive attributes for a tool, and attributes
which do not generally describe Rust's attitude toward things like
names and formatting.

If crates.io wishes to enforce that users not upload packages with
names like this, it should be enforced by crates.io at publish
time.

eminence/cargo,tshepang/cargo,rustyhorde/cargo,eminence/cargo,vojtechkral/cargo,tshepang/cargo,nipunn1313/cargo,rustyhorde/cargo,rust-lang/cargo,nipunn1313/cargo,rust-lang/cargo,tsurai/cargo,rust-lang/cargo,tshepang/cargo,rust-lang/cargo,nipunn1313/cargo,eminence/cargo,nipunn1313/cargo,vojtechkral/cargo,rustyhorde/cargo,tsurai/cargo,tsurai/cargo,rustyhorde/cargo,tsurai/cargo,vojtechkral/cargo,tshepang/cargo,eminence/cargo,tsurai/cargo,vojtechkral/cargo