Log Message:
py-pybtex: updated to 0.22.0

Version 0.22.0
Fixed handling of duplicate fields in .bib biles.
BibTeX parser is now up to 10% faster on some files.
Fixed parsing of names with \~ characters.
Fixed formatting proceedings without an editor field in unsrt.py.
In case of too many braces in a BibTeX string, PybtexSyntaxError is now raised \ 
instead of RecursionError.
Dropped 2to3, made the code compatible with both Python 2 and 3 with Six.
Moved tests outside of the pybtex package.
Fixed searching in docs with recent versions of Sphinx.
API: renamed bibtex.BibTeXEntryIterator to bibtex.LowLevelParser for clarity.
API: removed confusing usage of Person.text in tempate.names.
API: Entry.fields does not automagically look for cross-referenced entries anymore.