Added missing STL include of <list> in main.h
Removed duplicated include of <sstream>
Added comments on the background of min/max macro definitions and STL header includes

--HG--
branch : georg_d/fix_warn_minmax
In sparse matrix product, enable sorted insertion when doing two transposition is defenitely not optimal.
Fix SparseVector::coeffRef(i,j) and add missing SparseVector::insert*Unordered
Optimization in sparse-sparse matrix products for small ones
Merged in georg_drenkhahn/eigen/georg_d/fix_warn_minmax (pull request #81)

Fix for warning on macro definitions of max() and min() in test.h