Make "Related Topics" useful

The "Related Topics" section of a topic is confusing. Users expect the topics listed there to actually be related when, in fact, they often aren't. It's just a list of topics that are (poorly) chosen by some search algorithm. As a result users quickly learn to ignore that part of the Topic UI.

What's worse is that there is obvious and expected "related topics" functionality that is missing! There should be good way for users to manually specify topics that actually related.

Suggestion: Replace the current "Related Topics" section with a UI that ...
- Lists topics users have specifically marked as "related"
- ... (optional) or that are linked to from the topic or any replies/comments in the topic
- Provides an easy way to find topics and add them as a "related topic".
- Provides an easy way to search for and insert topic links into replies and comments.

For example ...

+----------------------------+


| Related Topics             |


|   - some related topic     |


|   - another related topic  |


|   - this one too           |


+----------------------------+


| Topic Search:              |


|  [search field here]       |


|   - result one             |


|   - result two             |


|   - result thre            |


+----------------------------+

Within the topic search section allow users to select one or more topics and "mark as related", or "get short url" (to insert into a reply) without having to leave the page.