Program sfstackn | Stack prespecified values. 
[SYNOPSIS]
sfstackn < in.rsf > out.rsf min=minin.rsf max=maxin.rsf mean=y thres=0.
[PARAMETERS]
string  | max | = |   | 	file determining up to which value to stack (auxiliary input file name)
bool    | mean | =y |  [y/n] | 	if n, sum; if y, average 
string  | min | = |   | 	file determining from which value to stack (auxiliary input file name)
float   | thres | =0. |   | 	threshold (percentage of maxabs) 
[DIRECTORY]
user/saragiotis
