Make option_map_unwrap_or and option_map_unwrap_or_else allow by default

[killercup]

One of the lints I ignore most often is option_map_unwrap_or.

The docs say:

What it does: Checks for usage of _.map(_).unwrap_or(_).

Why is this bad: Readability, this can be written more concisely as _.map_or(_, _).

I think having two method calls with one parameter makes the intent clearer than using one with two parameters (one method call per line does one thing). This may also keep the diff-noise down a bit.

The same goes for option_map_unwrap_or_else.

[leoyvens]

I've seen crates that disliked map_or so I'm in favor of this.

[Stebalien]

Worse, the argument order is confusing; personally, I'd lint against using this function. When I see map_or_else, I expect the first function to be the map function and the second to be the "else" function but it's actually backwards.