Production candidate: adds daily ArXiv indexing script

This point release adds a modified version of the daily ArXiv scripts that have been used to index ArXiv. The arxiv-specific shell scripts update.sh postprocess and index.sh were combined into a single shell script, with code related to non-indexing tasks (document matching, fulltext harvesting, reference resolution) removed. The additional perl program included with the script was originally an inline perl command embedded in the index script, and run via perl -e; it was separated out from the script into a stand-alone code to aid in clarifying the workflow.