reverted change to peerDependencies and todo comment

Author: frankwallis

package.json

@@ -38,8 +38,8 @@
     "timers": "fake"
   },
   "peerDependencies": {
-    "react": ">=15.0.0",
-    "react-dom": ">=15.0.0"
+    "react": "^15.0.0 || ^16.0.0",
+    "react-dom": "^15.0.0 || ^16.0.0"
   },
   "dependencies": {
     "chain-function": "^1.0.0",

src/TransitionGroup.js

@@ -76,6 +76,8 @@ class TransitionGroup extends React.Component {
       }
     }
 
+    // If we want to someday check for reordering, we could do it here.
+
     let keysToEnter = this.keysToEnter;
     this.keysToEnter = [];
     keysToEnter.forEach(key => this.performEnter(key, this.childRefs[key]));