Check Correc threshold for FCBF

[elbaulp]

Something like this:

if thresh < 0:
        thresh = np.median(slist[-1, 0])
        print "Using minimum SU value as default threshold: {0}".format(thresh)
    elif thresh >= 1 or thresh > max(slist[:, 0]):
        print "No relevant features selected for given threshold."
        print "Please lower the threshold and try again."
        exit()

From FCBF.py