Add the addFile and reset function to be able to manage file one by one

The idea is to be able to load files one by one after initialization. So I add the two methods :
- reset : empty the objs,
- addFile : read a file and adds the content the objs.

With these two methods you can easily loads more file after initialization or reset the content of the properties.

I hope you find this usefull and can merge into your master branch.

JM.