[GiNaC-devel] patch for simplify_indexed.

Dear developers, When simplify_indexed() is called two symmetrizations w.r.t dummy indices are performed. In these two cases symmetrization w.r.t. all dummy indices is done. However, it is also possible to do symmetrization with respect to ordinary idx-es, varidx-es and spinidx-es seperately. The latter is potentially much faster. E.g. Today I had an example where some terms contained 5 ordinary dummy indices and 2 dummy indices with variance. In this case a factor of 21 fewer terms are generated by the latter option. (I.e. 7!/5!/2!=21). Therefore symmetrizing seperately can be much faster. A patch is attached. Best wishes, Chris