Finish "last comments" implementation

[planetcruiser]

Intro:

• We have an undocumented feature on  http://www.bewelcome.org/lastcomments displaying the last comments members gave each other

Task:

• Feature should be made easily accessible to all members
• Privacy needs to be respected

Solution:

1. Link feature from a prominent location, options:
   • Personal homepage (after login)
   • Main menu, possibly under "Explore"
2. Add checkbox to add comment page: "Show in latest comments" (with note about preference below)
3. Allow members to set preference for checkbox

Concerns:

• Comments in stream are out of context
• Possible invasion of privacy
• Negative comments on last comments page might influence honesty

Related tickets:

• #1262