Set genetic code

This function allows the user to change the default genetic used in all the options. It is possible to select the standard code, the mammalian mitochondrial code, the yeast mitochondrial code or read in a file containing a personal code. The personal code must be in the same format as that used for defining the codon frequency tables. See section Codon usage method

The code differences are:

           Mammalian        Yeast
    Codon  Mitochondrial  Mitochondrial  Standard
     UGA       W              W            STOP
     AUA       M              M             I
     CUA       L              T             L
     AGA      STOP            R             R