allow set max_id and min_id for MessageIter and SearchIter

[amone-bit]

allow set max_id and min_id for MessageIter and SearchIter to filter messages like telethon.

[Lonami]

Why is the existing offset_id and breaking out of the loop early not enough?

[amone-bit]

If I use offset_id I need to filter messages in local, and will fetch more data from server. I think that will cost more time, and may not be very elegant and efficient. In the contrary, if I set min_id and max_id the filter will in telegram server, and will return less data from server. And meanwhile min_id and max_id maybe more intuitive than offset_id and loop.

[amone-bit]

offset_id seems only can get older messages, can't get the new messages. I want to get messages from old to new rather than from new to old.

[amone-bit]

It would be very nice, if SearchIter and MessageIter have not only next() method but also prev() method to iter from behind to front.

[Lonami]

I've discussed this before and also argued it wasn't needed. But I may reconsider if more people need it.

One of my worries is that some offsets seem to not always work, and exposing them here would mean people would expect them to work.

If we introduce max_id, I think we should remove offset_id. And when making the request, continue using offset_id internally unless min_id was also set.

Regarding prev, I'm not sure it's a good idea to provide both at the same time. If anything, there should be some sort of .reversed(), kind of like in Telethon. But we also need to be very careful here, to make sure it works in all edge cases. And it's more maintenance burden.