MT Declustering tests

[Giuseppe Vallarelli]

declustering test cases:

1. All events are flagged as within a cluster (input file decluster_test_cat_all_cluster_aftershock_2.csv)
expected output: vcl [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1], vmain_shock (first row of the input file), flag_vector [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]

2. No events are recognised as occuring within a cluster (input file decluster_test_cat_no_clusters.csv)
expected output: vcl [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0], vmain_shock (as the original catalog), flag_vector[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]