Made the Chattable and Fileable interface methods exportable.

[edyapups]

It is very strange that these interfaces could not be implemented outside the package in the first place. Since many methods are not represented in the package (answerCallbackQuery for example), there is obviously a need to create the methods by yourself and it would be very convenient to be able to make requests through Request(c Chattable).

[kateile]

This needs to merged