update refactored natural_sort function in show_trait/SampleList.py
update refactored natural_sort function in show_trait/SampleList.py

pjotrp/genenetwork2,zsloan/genenetwork2,zsloan/genenetwork2,genenetwork/genenetwork2,genenetwork/genenetwork2,pjotrp/genenetwork2,pjotrp/genenetwork2,genenetwork/genenetwork2,genenetwork/genenetwork2,pjotrp/genenetwork2,zsloan/genenetwork2,pjotrp/genenetwork2,zsloan/genenetwork2