Editing comments as a logged in user

[Konfuz]

As far as i can see there is no function that allowes an logged in user to edit his comments.

The function to delete a comment is existent, so one might delete the old comment and write a new one.

It would be most statisfying to have the option to edit the comments.
Perhaps it would also be wise to inform users that a comment had been edited and eventually provide some sort of history.

[opatut]

Kind of related to #43 and #44. Will do.