_updateInternalProperties() {
        this.selection = AutoNumericHelper.getElementSelection(this.domElement);
        this.processed = false;
    }
Update the selection values as well as resets the internal state of the current AutoNumeric object.
This keeps tracks of the current selection and resets the 'processed' state.

Note : This state can change between the keydown, keypress and keyup events, that's why
       this function is called on each event handler.

@private