Biblatex enhancements

I've added several enhancements for biblatex discussed in different places.

- Type for thesis, (defaults to phdthesis if type is empty or if "phd" is found in type, as discussed here: #638)
- getCollections : true (see: d0eec765e4baf995250e42f9d3c5fad83c94dff7)
- `@inbook` and `@collections` in some cases ([discussion on zotero forums](https://forums.zotero.org/discussion/34380/biblatex-translator-and-incollection-entry-type/))
- More languages for `langid`. (only babel is supported though, adding support for polyglossia as [discussed here](https://forums.zotero.org/discussion/33960/biblatex-importexport-csl-language-biblatex-langid/#Comment_176218) would necessitate some kind of switching mechanism: It could be either babel or polyglossia, not both, since language names differ)

I've done some fairly extended testing and am pretty sure that I've not introduced any new bugs this time :smile:, but this certainly means changed behaviour (on features I guess very few people rely on right now though).

(I thought two commits was fairly reasonable, but maybe you would like them squashed?)