Fix mess in issues

Either give us Markdown live-preview (issue not even touched or assigned for past two years) or an ability to edit and delete all the comments!

Current implementation results in unbelievable mess and is not acceptable!

Without Markdown live-preview, have to do a real-save (and we're ending with another auto-generated comment about edit made) even if we change one letter in a text. This runs into an unbelievable mess. Comments added to issues become nearly useless, because there are "lost" among sometimes hundreds of auto-generated ones!

I can't count how many issues were only partially solved by me, because I missed something important, added in a comment, because this comment was surrounded by many useless, not-editable, not-removable, auto-generated comments, added after each edit to main issue text, after changing a milestone, component, priority, kind, assignee etc.

I know and understand, that you're treating BitBucket like an orphan child (because it is free for most users) and you're focusing all your powers on JIRA. But... for God sake, how do you want us to consider buying paid version of BitBucket, if demo (free version) lacks key, fundamental features for years?