Fix sort method: same as in solution_sort file

cadbiom/models/clause_constraints/mcl/MCLSolutions.py

@@ -383,8 +383,7 @@ class FrontierSolution(object):
         The format is readable by the simulator
         @param outfile: writable file
         """
-
-        outfile.write(' '.join(sorted(self.activated_frontier)) + '\n')
+        outfile.write(' '.join(sorted(self.activated_frontier, key=lambda s: s.lower())) + '\n')
         outfile.write('\n'.join(self.ic_sequence) + '\n')
         outfile.flush()