Use `required-features` example property instead of `compile_error!`

[JohnTheCoolingFan]

This will make cargo enable features needed for the example automatically without the need for checks in teh example via cfg directives

[erwanvivien]

Could I rebase the commits in your branch and merge ? :)

[JohnTheCoolingFan]

Yes

[erwanvivien]

Big thanks, those are cool changes! I didn't know required-features