Separate since_id for search and mentions

Hello,

I have a twitter bot running and decided to make it a little bit smarter. I would like to able to treat mentions different from results of a search query: I want my bot to behaviour in on way when tweets come from a search and differently and they come from mentions.

The feature I'm currently looking for is give users the ability to mute my bot (I don't want to spam anyone, so people should be able to tell my bot to shut up).

The problem I faced is that `since_id` works for both search and mentions. Which means that If I run the search first, I might lose some mentions tweets due to tweets ids. And, in the same way, if I process mentions first I may lose some search results.

What I did was to create a new config called `since_id_reply` that will not interfere in the `since_id` used by search.

I'm not sure if such behaviour is desired, so I'm kinda bringing up the discussion: is this feature interesting to everyone? Did I miss something? Could I have done it in a easier way?

Feedback is welcome.