Move to IEEE transactions reference style

[ppietikainen]

We want to stop maintaining our own reference style (Acta Oulu 1999) and use real IEEE Transactions instead, IEEEtran.bst . Small problems:

• Finnish support (s. instead of p.), maybe not a problem
• Zotero etc. use a DOI field, which is ignored by the official IEEE style file. https://github.com/maxkratz/ieeetran_doi or similar should work, just find the best one that makes things smooth and use that in this template.

[ppietikainen]

Done in #10 & #14