Support --path option in highlight query

[staabm]

this PR adds a --path option for the highlight command.
refs #237

this is meant as a simplified initial proposal so I can get early feedback.
after we agreed on how this option should look like in the highlight-case, I will adjust the remaing 2 commands accordingly.

Todo

• support the new option in lint-command
• support the new option in tokenize-command

[staabm]

initially I named this option --file, but this somehow collides with the --format option when using getopt (I guess because of the same first character or something).

to get arround this naming problem I renamed the option to --path.

If you like --file more I can do the changes, after someone guided me on how the opts-format needs to look like.

[staabm]

Just implemented the stdin reading case in #239

this might make this change here obsolete. please tell me your feeling whether supporting this parameter still makes sense, or whether people should just use
cat my.sql | bin/highlight-query or similar instead of bin/highlight-query --path=my.sql

[devenbansod]

I'm in favor of the stdin approach in #239 (though I don't have a very strong opinion on it and could be convinced otherwise) because I find it sleeker and more pluggable over this approach.

[staabm]

I totally agree.

[devenbansod]

Thanks for opening this PR.

I'm closing this and we'll continue the discussion at #239. 👍

[ibennetch]

I think this is an awesome improvement and I’m really looking forward to getting it implemented. I don’t have a strong feeling about whether this or the other is a better approach, but Deven‘s reasoning seems sound. The stdin approach is more flexible for piping and I don’t see any compelling reason to favor this approach.