'Reset a field set:
* clear fields ;
* restart field generator ;
* set current size to zero ;
* clear field array count.
But keep: name, value, description and size.'

def reset(self):

    BasicFieldSet.reset(self)
    self._fields = Dict()
    self._field_generator = self.createFields()
    self._current_size = 0
    self._array_cache = {}
