edit and enhance developer_guide.rst
edit and enhance developer_guide.rst

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