months should be 3-letter macros

[cpmpercussion]

some months are literals (e.g., {"April"}) and some use the 3-letter macros (jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec).

3-letter macros are preferred because whatever bibstyle will turn them into the correct month name (in the correct language) when required.

so let's chip away at this over all the proceedings.

[alexarje]

Yes, good. I am not really sure if it is really necessary to include the month? Again, this is probably more relevant for some journals than for an annual conference.

[cpmpercussion]

I don't think it's super necessary either, but I guess it's there if people want to know 😄

actually it turns out to be a bit tricky to preserve the 3-letter macros with bibtexparser, so maybe better to go with the flow to use full months or just drop the month from the entries.

[alexarje]

I would skip the month. From a historical perspective, it would have been more interesting to have the conference dates in there, but I don't think that is very important either. Saving some bytes in the file is probably also nice from a parsing perspective.