XMPP message editing support

[ForNeVeR]

XMPP supports message editing (see XEP-0308) just as Telegram do (see #18).

This is a dual issue for #18: we need to get some insight on bots' ability to edit their own messages in Telegram and implement proper support for edited XMPP messages in the bot. So, when a user edits his/her message in XMPP, the edit should be transparently translated to Telegram.

Currently I doubt that Telegram bots can edit their messages; I'll ask the experts.

[ForNeVeR]

@leha-bot, I believe you know more about Telegram bots than me. Could you please enlighten us about bots' message editing in Telegram? Could a bot edit its own message or not?

[leha-bot]

Hello, @ForNeVeR . Yes, they can via editMessage method. Please take a note about the message_id parameter – you can get from a same JSON attribute message_id of sendMessage method's return value.