Unnecessary whitespace for selective model extension

[m-kessler]

The selective model extension, which mofmt supports since #6, is not formatted correct.

This code:

model NewPlant
  extends System(
    break controller,
    break reference);
end NewPlant;

Is formatted as:

model NewPlant

  extends System(
    break controller ,
    break reference );

end NewPlant;

Note the extra white spaces at the end of each break statement.

[ErykMroczek]

Fixed in d3c7293, so you can use this commit in pre-commit. For manual usage, use command cargo install --git.

It will be included in 0.6.0, but I will wait with the release until I implement HTML formatting.