Suggest missing `.` for typo in ranges

[Rageking8]

Given the following code: link

fn main() {
    for i in 0.10 {

    }
}

The current output is:

Compiling playground v0.0.1 (/playground)
error[[E0277]](https://doc.rust-lang.org/nightly/error-index.html#E0277): `{float}` is not an iterator
 --> src/main.rs:2:14
  |
2 |     for i in 0.10 {
  |              ^^^^ `{float}` is not an iterator
  |
  = help: the trait `Iterator` is not implemented for `{float}`
  = note: required for `{float}` to implement `IntoIterator`

For more information about this error, try `rustc --explain E0277`.
error: could not compile `playground` due to previous error

Ideally the output should suggest adding a . due to the typo. Thanks.

[estebank]

We might also want to handle the opposite case: let _: f64 = 0..10;

[leonardo-m]

Avoiding stuff like "in 0.10 {" is why I suggested that ".." is an operator, so the standard rustfmt formatting should have spaces around it, as in "in 0 .. 20 {".