working prototype of Abbyy parsing, no tests
abbyy downloader module get_abbyy
getabbyy: use md5 hash
probably right: refactor OOP
handle race condition, poorly tested
messy copypaste job: rowspan/colspan
md5 hash includes ocr params
Decouple 'is a file of type foo' from 'use FOOTableSet' in any; permit overrides
Tests for ABBYY override
Merge branch 'okfn-pdf'