made optional argument of SpikeGeneratorFromFile::rewind mandatory and updated docs
made optional argument of SpikeGeneratorFromFile::rewind mandatory and updated docs

UCI-CARL/CARLsim4,UCI-CARL/CARLsim4,UCI-CARL/CARLsim4,UCI-CARL/CARLsim4,UCI-CARL/CARLsim4,UCI-CARL/CARLsim4