Added tests for group files in read_param_file
Added groups flag to read_param_file function
Tests and implemented grous for read_param_file

Used csv,DictReader
Optional delimiters string to give a hint to the sniffer
Added test for make_index_list in morris_optimal
Added group functionality to morris_optimal

Added group arguments to compile_output, make_index_list and
compute_distance_matrix
Added a check function to ensure than the input sample is the correct
size
Added more group-related tests for morris class
Amended group treatment in morris class
Updated optimal_trajectories to handle groups