Intent to support allowed variables in no-underscore-dangle

Certain libraries use underscores half privately, half as a requirement. Ember _super is used to reference the parent class.

http://eslint.org/docs/rules/no-underscore-dangle.html

Would there be any interest in supporting a property where the user can specify allowed variables like:

"no-underscore-dangle": [2, { "allowed": ["_super"]}]

[ultrafez]

I’ve encountered another use-case for whitelisting, and that is when working with an API that uses fields beginning with underscores. My particular use-case is that I’m working with an API that exposes MongoDB objects, which have the key “_id”, which would be the perfect candidate for whitelisting.

[nzakas]

Okay, how about we just simplify here. We’re adding allow options to several rules, so we can do the same here. I’ll assume this is a void-your-warranty option so people who use it accept the possibility of it flagging more than expected.