bkmartinjr/#294 rest sort (#300)

REST API now requires that the server sort all dataframe responses by dimension index (var or obs index), allowing the client (front-end) to assume responses will be sorted. Given that the dataframe usually has a natural ordering, and the server gets to arbitrarily assign indices, this is the most computationally efficient design.

This PR includes changes to the REST API spec, and removing the explicit sort in the front-end code.

client/src/util/stateManager/universe.js

@@ -116,7 +116,6 @@ function RESTv02AnnotationsResponseToInternal(response) {
   const keys = ["__index__", ...names];
   return _(data)
     .map(obs => _.zipObject(keys, obs))
-    .sortBy("__index__")
     .value();
 }
 

docs/REST_API.md

@@ -302,7 +302,7 @@ Observations and variables are guaranteed to have a `name` annotation, which sho
 - 200 Success
 - 404 Not Found - one or more of the names specified with `annotation-name` are not associated with an annotation.
 
-**Response body:** annotation description and values. Values conform to the schema returned by `/schema` and each record begins with the observation or variable index. Where the specific value is not defined, `null`will be returned.
+**Response body:** annotation description and values. Values conform to the schema returned by `/schema` and each record begins with the observation or variable index. Where the specific value is not defined, `null`will be returned. Values will be sorted by index.
 
 Example:
 
@@ -369,7 +369,7 @@ Get data from the dataframe (ie expression values), optionally sub-selected by a
 - 406 - Not Acceptable (accept-type unacceptable MIME type)
 - 400 - Bad Request - malformed filter
 
-**Response body:** contents of the filtered dataframe, in primary-axis-major order, encoded as a dense matrix (eg, `/data/obs` will return data by observation). Data is preceded by a list of secondary axis indices, using the same index encoding as Index Filters (ie, an array of indices and/or index ranges). In JSON, this will be encoded as an array of indices with key obs or var; in CSV, this will be the header of the CSV response body.
+**Response body:** contents of the filtered dataframe, in primary-axis-major order, encoded as a dense matrix (eg, `/data/obs` will return data by observation). Data is preceded by a list of secondary axis indices, using the same index encoding as Index Filters (ie, an array of indices and/or index ranges). In JSON, this will be encoded as an array of indices with key obs or var; in CSV, this will be the header of the CSV response body. In both encodings, data will be sorted by index (both primary and secondary axis).
 
 Example JSON response to a request which has filtered by annotation value:
 
@@ -428,7 +428,7 @@ If re-clustering is not supported by the server, must return an HTTP 501 respons
 
 **Response body:**
 
-- For 200 Success, returns numeric cluster ID for each observation or variable, organized as an array of `[index, clusterId]`:
+- For 200 Success, returns numeric cluster ID for each observation or variable, organized as an array of `[index, clusterId]`, an sorted by index:
 
   ```
   {
@@ -446,7 +446,7 @@ If re-clustering is not supported by the server, must return an HTTP 501 respons
 
 Get the _default_ layout for all observations or (_future_) all variables. Return dimensionality of layout and a coordinate list. The client must be prepared to accept dimensionality different than it natively displays, and should perform a best-effort attempt to display the higher dimensionality layout (eg, create a 2D view of a 3D layout).
 
-**Response body:** dimensionality and coordinate list for each observation or variable, where coordinates are encoded as floats [0,1]. Example 2D response:
+**Response body:** dimensionality and coordinate list for each observation or variable, where coordinates are encoded as floats [0,1], sorted by index. Example 2D response:
 
 ```
 {