Fix to not use diff_cleanupSemantic, bug report refer to https://code.google.com/p/google-diff-match-patch/issues/detail?id=67

Author: jackycute

lib/workers/dmpWorker.js

@@ -57,7 +57,6 @@ process.on('message', function(data) {
 function createPatch(lastDoc, currDoc) {
     var ms_start = (new Date()).getTime();
     var diff = dmp.diff_main(lastDoc, currDoc);
-    dmp.diff_cleanupSemantic(diff);
     var patch = dmp.patch_make(lastDoc, diff);
     patch = dmp.patch_toText(patch);
     var ms_end = (new Date()).getTime();