Clade file format

The user is allowed to specify some invariant clades to reduce the number of possible topologies when using mlphase. A clade file contains a list of monophyletic clades in newick format. All studied species must appear once (and only once) in the file, either alone or in a clade. Here is a simple clade file example for 6 species:
(Specie5,Specie6);
(Specie4,(Specie3,Specie2));
Specie1;