add docstring to use_first_available()
add docstring to use_first_available()

rc/sfepy,BubuLK/sfepy,BubuLK/sfepy,BubuLK/sfepy,sfepy/sfepy,sfepy/sfepy,vlukes/sfepy,vlukes/sfepy,rc/sfepy,sfepy/sfepy,vlukes/sfepy,rc/sfepy