+ new F81/EI transformation formula using gamma shape parameter (option -a 1.5 by default) + option -f to to use the 4 nucleotide frequencies in F81/EI transformation; by default, to deal with multiple contig files, JolyTree sets f(A)=f(T)=0.5*(A+T)/(A+C+G+T) and f(C)=f(G)=0.5*(C+G)/(A+C+G+T) + option -s modified to specify sketch size as a fixed integer or as a proportion of the average genome size