jydiss 1.15a

Corrected release 1.15.

Changes to jydiss.cls:
– Correct float separation
– Do not output empty lines to the abstract page when data is missing
– Add an “yhteenveto” environment for Finnish summaries
– Add commands \series and \issn

Changes to jydiss.bbx:
– jydiss.bbx: Use correct headers and footers for the bibliography
– Improvements to jydiss.bbx handling of dates and In-punctuation