Zotero BibTeX keys do not account for cite key collision

[wshanks]

See discussion in #28. The Zotero cite keys are generated by running the citation through the export translator individually, so there is never any collision in the translator processing. When generating a full bibliography with the translator, it accounts for collisions and disambiguates by adding a number to the end of the duplicate key. Perhaps there is a way to distinguish the items in LyZ using the translator functions. If not, the full bibliography could be parsed to match up items to bibliography entries in order to match de-duplicated cite keys to the correct Zotero items.