Release Strata version 2.0.0-alpha.119.

 * Remove leaf/branch comparator distinction. Closes #788.
 * User must provide extractor and comparator. See #788.
 * Parital search. See #788.
 * Partition using a partition length.
 * Composite keys only. See #788.
 * Fix comparison against `null`.
 * Upgrade `reciprocate` to `0.0.9`.
 * Preparing for a change to array keys only.

Closes #789.

package.json

@@ -1,6 +1,6 @@
 {
     "name":                 "b-tree",
-    "version":              "2.0.0-alpha.118",
+    "version":              "2.0.0-alpha.119",
     "description":
 
       "Async/Await I/O B-tree in pure JavaScript for Node.js.",