Habanero

* `filter_names()` and `filter_details()` altered to get metadata for works, members and funders filters; and added egs to members and funders methods for using filters (67)
* many typos fixed (80) thanks Radcliffe !
* use of a progress bar is now possible when fetching works route data, only when doing deep paging, see `progress_bar` parameter (77) (82)
* `content_negotiation` fixes: `ids` parameter is now required (has no default), and must be a str or list of str (83)
* no longer testing under Python 2

* Added verification and docs for additional Crossref search filters (62)
* Big improvement to docs on readthedocs (59)
* Added `mailto` support (68) (63) and related added docs about polite pool (66)
* Added support for `select` parameter (65)
* Added all new `/works` route filters, and simplified filter option handling within library (60)

* Now using `vcrpy` to mock all unit tests (54)
* Can now set your own base URL for content negotation (37)
* Some field queries with `works()` were failing, but now seem to be working, likely due to fixes in Crossref API (53)
* style input to `content_negotiation` was fixed (57) (58) thanks talbertc-usgs
* Fix to `content_negotiation` when inputting a DOI as a unicode string (56)

* Added more documentation for field queries, describing available fields that support field queries, and how to do field queries (50)
* `sample` parameter maximum value is 100 - has been for a while, but wasn't updated in Crossref docs (44)
* Updated docs that `facet` parameter can be a string query in addition to a boolean (49)
* Documented new 10,000 max value for `/works` requests - that is, for the `offset` parameter - if you need more results than that use `cursor` (see https://github.com/CrossRef/rest-api-doc/blob/master/rest_api.md#deep-paging-with-cursors) (47)
* Added to docs a bit about rate limiting, their current values, that they can change, and how to show them in verbose curl responses (45)
* Now using `https://doi.org` for `cn.content_negotation` - and function gains new parameter `url` to specify different base URLs for content negotiation (#36)
* Fixes to kwargs and fix docs for what can be passed to kwargs (41)
* Duplicated names passed to `filter` were not working - fixed now (48)
* Raise proper HTTP errors when appropriate for `cn.content_negotiation` thanks jmaupetit (55)

- fixed problem with `cr.works()` where DOIs passed weren't making the correct API request to Crossref (40)
- added support for field queries to all methods that support `/works` (https://github.com/CrossRef/rest-api-doc/blob/master/rest_api.md#field-queries) (38)

- user-agent strings now passed in every http request to Crossref, including a `X-USER-AGENT` header in case the `User-Agent` string is lost (33)
- added a disclaimer to docs about what is actually searched when searching the Crossref API - that is, only what is returned in the API, so no full text or abstracts are searched (32)
- improved http error parsing - now passes on the hopefully meaningful error messages from the Crossref API (31)
- more tests added (30)
- habanero now supports cursor for deep paging. note that cursor only works with requests to the `/works` route (18)