Fix: Stop splitting surrogate-pairs in diff-match-patch deltas

See google/diff-match-patch#80

There have been certain cases where consecutive surrogate pairs crash
`diff-match-patch` when it's building the _delta string_. This is
because the diffing algorithm finds a common prefix up to and including
half of the surrogate pair match when three consecutive code points
share the same high surrogate.

```
// before - \ud83d\ude4b\ud83d\ue4b
// after  - \ud83d\ude4b\ud83d\ue4c\ud83d\ude4b
// deltas - eq \ud83d\ude4b\ud83d -> add \ude4c -> eq \ud83d \ude4b
```

This crashes when trying to encode the invalid sequence of UTF-16 code
units into `URIEncode`, which expects a valid Unicode string.

After the fix the delta groups are normalized to prevent this situation
and the `node-simperium` library should be able to process those
problematic changesets.

Author: dmsnell

RELEASE-NOTES.txt

@@ -1,5 +1,9 @@
 # Changelog
 
+## 1.0.2
+
+ - Update diff-match-patch to fix problem when encoding consecutive surrogate pairs
+
 ## 1.0.1
 
  - Disconnect from existing socket connection when connecting [#90](https://github.com/Simperium/node-simperium/pull/90)

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "simperium",
-  "version": "1.0.1",
+  "version": "1.0.2",
   "description": "A simperium client for node.js",
   "main": "./lib/simperium/index.js",
   "repository": {