remove leftover 2.5 compatibility code
remove double cast (const char*)(char*)
Merge pull request #349 from larsmans/cleanup

Minor cleanup (2.5 compat, mostly)
Merge branch 'master' of https://github.com/cython/cython into reverse_range_optimize
Optimized code generation reverse case that uses variables, although there is probably a solution that is more natural within the compiler structure.