Add .editorconfig template on crystal init command.

[akzhan]

Settings based on https://github.com/crystal-lang/crystal/blob/master/.editorconfig.

Refs #297.

[asterite]

This project (Crystal) uses this editor configuration, but other Crystal projects are free to use whatever configuration they want. I don't think this should be included in every Crystal project.

[oprypin]

Are other Crystal projects not free to use a different license?

[akzhan]

@asterite this .editorconfig just follow crystal language convention at all. Like crystal tool format one.

No one requires to use it, but it is fine default. Like use git by default etc.

[RX14]

I think including an editorconfig file is a good default, just like the gitignore and license we include.

[asterite]

OK, sorry, I shouldn't have closed this. Have someone else decide :-)

[mverzilli]

Thanks!