Add `--filename` option

[MaximDevoir]

It would be great if ncc build supported an option such as --filename to allow naming the generated file to something other than index.js.

It looks like the application was built to support this option in the future with the following lines already in place:

https://github.com/zeit/ncc/blob/0ad6971d202ee5896310f65e9aedfd1156184346/src/index.js#L39

https://github.com/zeit/ncc/blob/0ad6971d202ee5896310f65e9aedfd1156184346/src/index.js#L53

https://github.com/zeit/ncc/blob/0ad6971d202ee5896310f65e9aedfd1156184346/src/index.js#L131-L134

[tunnckoCore]

I "wanted" such feature in the beginning. The answer to that is you can name the out folder however you want. And I can agree with that, plus consistency - output will always end in index.js

[internettrans]

I talked to @guybedford about this today - he said the js api supports this and he'd be open to a PR adding support for changing the output filename via CLI

[tcurdt]

I am a little confused - why did you close the issue, @MaximDevoir ?