Better timestamps for Private Messaging

Currently the timestamps for Private Messages only show a relative value (in the frontend as well as the Control Panel). Like:

• 3 hours ago
  
• 5 days ago
  
• 6 months ago
  
• 1 year ago
  

Our moderators occasionally struggle with this.

Example:

• A customer was in contact with a moderator via Private Message.
  
• In a PM with the timestamp "1 day ago" the customer wrote "My internet is not working at the moment".
  
• The moderator took a look into the internal customer database and could see a ticket was created (and closed as "fixed") at a certain date and time.
  
• What the moderator couldn't determine was if the customer has been writing the PM before or after the ticket was created and fixed.
  
• So it wasn't clear if the customer was reporting a new problem (before the ticket was created) or a reoccuring problem (after the ticket was closed as fixed)
  
• The moderator was forced to ask the customer about the state of the issue. With a better timestamp it would have been clear what the status was when the PM was sent.
  

That's why I propose that, at least in the Control Panel, all Private Messages get a Date/Time timestamp (like it is already present in the forum overview and topic moderation). This will help moderators provide a better customer service and better customer experience.