TRACKING: Message rendering bugs/enhancements

[neiljp]

• [ ] Empty link bug #1103
• [x] Render heading titles #1095
• [ ] Render horizontal rulers
• [x] #691 : Mentioning times (with automatic time zone adjustment) [PR #765]
• [ ] #688 : Spoilers
• [ ] #402 : quoting (other cases may be present)
• [x] #618 : List links at end of message (and/or in popup?) [also see #424 PR] (fixed in #703/#708)
• [x] Render tables (#550)
• [x] #352 : Interpret internal links to messages in other streams/topics, and handle them [PR #708]
• [ ] #359 PR: Images in the default browser [also PR #740, #1058, #1223]
• [x] #397 PR: Viewing a message in the browser [also PR #698]
• [ ] #415 Ascii images

[preetmishra]

Update: 4: List links at end of message (and/or in popup?) has been resolved in #703 and #708.

[zee-bit]

Update: The last point (Add a key to view a message in the browser) has been resolved through #991.