gitlint: add flags option

[bmrips]

The gitlint hook requires --msg-filename to appear last on the command line such that it is in front of the commit message filename. This is not the case when the args option is set. To fix this, we append --msg-filename to the args option.

Fixes #641.

[sandydoo]

args are for end users to set. If a hook is designed in such a way that it cannot handle filenames as arguments, ie. without an option like --msg-filename, then we usually expose a settings.flags or, better yet, individual options.

[bmrips]

I agree that the design of gitlint's CLI does not come in handy. With a flags option, however, we loose forward compatibility.

[sandydoo]

With a flags option, however, we loose forward compatibility.

Not entirely sure what you mean by that

[bmrips]

Not entirely sure what you mean by that

If we add gitlint.flags.* options and gitlint changes its CLI flags, we would have to keep them in sync.

[sandydoo]

If we add gitlint.flags.* options and gitlint changes its CLI flags, we would have to keep them in sync.

Ah, I get it now. That's if we add individual settings.*. By flags I mean what a lot of the other hooks do: an array of strings. It's exactly like args, but can appear in docs and it's position can be controlled.

As far as API changes, that isn't a big deal in practice. These hook tools rarely change in practice. And if they do, well, we fix it here.

[bmrips]

Ok, I added the gitlint.flags option.