Proposed fix for 1150 Preset Browser: division between factory and user ...

Proposed fix for  #1150 Preset Browser: division between factory and user files fails if factory has folders

![image](https://cloud.githubusercontent.com/assets/7412852/5557268/0204f98e-8cef-11e4-8bd2-a65722ec8ad3.png)

Simply added a counter to the Directory class. that is incremented for every child directory added.

Then used this counter to calc the position in tree of --Factory Presets --