Version changes to the main Issue/MR body text
Description
Currently editing the main body text of an issue is a destructive process. If I edit it, nobody can say what was there exactly before I edited it. Even MR commits already have versions!
Proposal
We should be able to go back in time, plus have a system message, mentioning the version change and/or diff.. like currently sort of happens with the issue title!
Links / references
This would eventually also be a feature of: https://gitlab.com/gitlab-org/gitlab-ce/issues/4199
cc: @JobV @awhildy @godfat @tauriedavis @cperessini @hazelyang @jschatz1 @pedroms