Add changelog for the coming 0.7.4 release

[robinlinden]

@theAkito Anything you think is missing? Would it be worth mentioning that this is likely the last release with Android 4.4 support?

[theAkito]

Looks good. The chat history export is the backup thing, right?

Perhaps, it may be added, that image support was improved or something like that. 10d3030

Otherwise, I can only think of behind the scenes stuff, that does not belong in there, anyway.

[robinlinden]

Looks good. The chat history export is the backup thing, right?

Right. :P

Perhaps, it may be added, that image support was improved or something like that. 10d3030

We ended up having to revert that as it caused lots of flickering with ongoing file transfers. :( We'll give it another go after this release when we can use things that are a bit newer than the options we have right now.

Thank you for having a look! :D

[robinlinden]

We're planning a c-toxcore release, so will mention c-toxcore 0.2.19 in the readme and update that before actually tagging things. :P