- Update taxonomy documentation.
- Add URL for adding an individual category to a taxonomy.
- Add URL for getting details of top-level categories in a taxonomy.
- Perform log writes in a subthread. Logging now places items to write on
a queue of limited size, which is read by the logger thread; if this
queue becomes overloaded, a count of missed messages will be displayed.
- For ID and exact fields which have been truncated or hashed, do the
corresponding action at search time.
- Some compile fixes.