[WIP] Add Tox Chat Logs Standard specification

[SkyzohKey]

This PR adds Tox Chatlogs Standard spec to be part of the designs list.

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This change is 

[nurupo]

I don't think that forcing a standard for storing logs (also savedata files, friends' avatars -- just about anything) in some specific format is a good idea. A better idea is to let clients store data in which ever way they want but provide an option to export logs in a common format that could be imported into another client.

[anthonybilinski]

I agree with nurupo. qTox leverages a sql db that they we offload work to, and other clients may want to be lighter, have less dependencies etc and not want to use a full db. Having a shared export format seems fine, but having a shared save format would be a big change for clients.

[iphydf]

@SkyzohKey I think making an export format standard makes sense. What do you think?

[SkyzohKey]

This basically is the same. The main goal of having a standard chat logs format is that user' can easily switch between clients while keeping the same chat history with friends. Also, if you except the user to press a button, the ''exported'' logs will rapidly become out of sync. Do it whatever way you prefer, just made a ''standard'' for logs so it's easily read by humans and parsed by computers. How you guys want to use that is up to you 😜