bump version

package-lock.json

 {
   "name": "@logilab/libview",
-  "version": "0.6.3",
+  "version": "0.6.4",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {

package.json

 {
     "name": "@logilab/libview",
-    "version": "0.6.3",
+    "version": "0.6.4",
     "description": "Library for view specification and definition for a data browser.",
     "repository": {
         "type": "mercurial",