Refactored the indexing code to extract the domain-specific parts.

Also renamed some files to avoid confusion about which configuration file is which.
Fix for queryindex to input the correct backend settings code.
Moved the field name text search aliases from the query handling code to the indexing settings.
Made the field value constraint and count by value view respect field aliases (rather than only text search).
Added a CSS config file (for extra site-specific CSS) on the frontend.
Fix for storing non-unicode string types.
Moved description HTML generation to the frontend.

The backend now sends a configurable set of fields to the frontend in response to a description view request. The frontend produces suitable HTML from these fields.
Made config.mk for the frontend apply after the files settings variables; removed config.css.

There is no need for config.css now because you can add arbitrary CSS files in config.mk.
Factored out frontend description list generation code.
Comment in the frontend makefile to clarify how config.mk works.
Indexing the argument values.
Moved field name aliases to domain indexing file.
Factored out HTML description replacement code and merged some fixes and cleanup for it from the avherald branch.
Added organization text to the index, following the change in the avherald branch.
Moved Wikipedia base URL constant from backend config file to Wikipedia history domain file.
Added unstemmed predicate to index.
Added predicate to titles in description list.
Sentence field and use of sentence field instead of full description in the frontend event listing.
Better absolute URL detection in description generation.
More flexible system for replacements in description HTML; bolded predicate in description HTML; changed title in description list to be the event root.