4003 & 4011 Show timestamps in inbox & tweak preference help text

https://code.google.com/p/otwarchive/issues/detail?id=4003
https://code.google.com/p/otwarchive/issues/detail?id=4011

In your inbox, timestamps were not showing up for comments left by logged in users.

The help text for "Turn off copies of your own comments." said, "Enable this option if you prefer not to receive emails or inbox notifications for your own comments (for example, when you reply to comments on your own works)." This implied inbox notifications might be sent for your own comments. Since this is not and has never been true, "or inbox notifications" has been removed from that sentence.
Do you think it should be a separate string, or combined into `<%= ts('Anonymous Creator on') %>`? (I wonder if it would be a good idea to make it a config setting in the future, so we or anyone else using the software could easily change it in all the places it's used...)