To support apps which want to collect many changes and submit them together (to preserve bandwidth, or improve performance, or deal with being offline), reading lists should support batch operations (e.g. creating or deleting many list items at once).
To decide:
* which operations should this include? (list item creation/deletion? list creation/deletion/update?)
* should there be a batch version of each endpoint (e.g. `POST /lists/{id}/entries/` could take an array of list objects instead of a single one - a bunch of work but would make it possible to implment them efficiently with batched DB queries) or one single batch that takes a list of `[operation_type, param1, param2...]` items (easy to do, but we'll have to translate them to lots of single-row DB writes)?
* how do you pass an arbitrarily long list of paramters to the action API?
** use an `x-www-form-urlencoded` parameter such as `project1|title1|project2|title2|...` (ugh)
** use a JSON-encoded string as an `x-www-form-urlencoded` parameter (double ugh)
** use JSON in the POST body (a departure from API conventions; we claim that the API supports XML etc. clients as well)