`proceedings` is a `book` - e.g. the collection of conference papers

proceedings -> book mapping is used in pandoc (https://github.com/jgm/pandoc-citeproc/blob/master/src/Text/CSL/Input/Bibtex.hs) and citeproc-java (https://github.com/michel-kraemer/citeproc-java/blob/master/src/main/java/de/undercouch/citeproc/bibtex/BibTeXConverter.java)
map `school`, `institution` and `organisation` to `publisher` field.

This addresses issue #85.

Also some reformatting to accommodate longer names.

Such field mapping is used by pandoc (https://github.com/jgm/pandoc-citeproc/blob/master/src/Text/CSL/Input/Bibtex.hs) and citeproc-java (https://github.com/michel-kraemer/citeproc-java/blob/master/src/main/java/de/undercouch/citeproc/bibtex/BibTeXConverter.java)
`@misc` type support: no explicit type and `howpublished`->`publisher`

Rather than masquerading `@misc` type as `@article`, avoid giving it any CSL type. This would allow implementing `@misc` handling as “catch all” within a CSL style.

Also, map the `howpublished` field of `@misc` to `publisher`. This addresses issue #72.

Such type mapping is used by pandoc (https://github.com/jgm/pandoc-citeproc/blob/master/src/Text/CSL/Input/Bibtex.hs - e.g. `misc` becomes `NoType`). However, citeproc-java does not seem to support `@misc` altogether.
Merge pull request #86 from andriusvelykis/bibtex-citeproc

BibTeX citeproc updates: missing fields and 'proceedings' and 'misc' types