introduce sgroupby()
merged worksheets of critical and important RHSAs
swap columns of synopsis and keywords of RHBAs by keywords
sort out tables in xls; add rhsa_{cri,imp}_latests, merge rhsa_{cri,imp} into one, split xls files (summary and details), etc.
just re-format
change log level and make 'Dump metadata...' is not out by default
fine tunes in log messages
update the translation template and Japanese translation
swap worksheets of errata and updates in errata_details.xls