remove useless history in acoustics example
remove useless history in acoustics example

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