fix EquationMap._init_empty() to initialize n_epbc
fix EquationMap._init_empty() to initialize n_epbc

BubuLK/sfepy,lokik/sfepy,RexFuzzle/sfepy,rc/sfepy,lokik/sfepy,lokik/sfepy,vlukes/sfepy,RexFuzzle/sfepy,RexFuzzle/sfepy,RexFuzzle/sfepy,vlukes/sfepy,BubuLK/sfepy,rc/sfepy,rc/sfepy,vlukes/sfepy,BubuLK/sfepy,sfepy/sfepy,sfepy/sfepy,sfepy/sfepy,lokik/sfepy