Change exchange dependency in DataFeed

[ramilexe]

DataFeedSubscription accepts exchange service.Exchange but uses only CandlesSubscription method from Feeder interface. Does it make sense to change dependency from Exchange interface to Feeder?

[rodrigo-brito]

Hi @ramilexe, thanks for the suggestion!
Of course, both will be compatible. But in theory they are internal modules, this should not affect external users, are you having any problems with this point?

[ramilexe]

yes, I would like to use future.WsCombinedKlineServe method and instead of just implementing CandlesSubscription method and some other from Feeder I also need to implement Broker methods as well.

[rodrigo-brito]

Please, can you open a PR with this change?

[ramilexe]

@rodrigo-brito here we go #258