TRIVIAL: forgot to remove the href
PERF: reduce storage requirements for incoming links

Only store incoming links for topics.
Annotate changes
PERF: refactor incoming links table
PERF: finalize porting to new incoming links structure
remove invalid join
PERF: store topic views in a topic view table

* cut down on storage of the work Topic, 3 times per row (in 2 indexes)
* only store one view per user per topic
* only store one view per ip per topic