String Index API

This module instantiates an API into the string translation and theme processes to create unique indexes of string use instances, such that they can be invisibly attached to their appearances in the UI. This can then be used to trace the source (module, database, theme etc) of a string for translation or source replacement. Alternatively it can compile string use logs for offline analysis.

A couple of other use cases here are for interface translation where the same phrase and source string may need to be translated or replaced differently under different contexts.