add output_dir argument to homogenization-based material functions
add output_dir argument to homogenization-based material functions

- update get_homog_coefs_linear(), get_homog_coefs_nonlinear()

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