Allow opting out of ES3SafeFilter.

We were forced to move the `ES3SafeFilter` step to only operate on transpiled ES6 output (since it fails on some ES6 module syntax).

Sadly, this means that we are reprocessing the ENTRIE app/ tree for every rebuild.  Which is **SLOW**!!
small comment here please:

```js
// for some large projects, you may want to uncomment this (for now)
```