prevent transient leaks of file handle by using new helper functions These leaks may occur in environments that don't employ a reference counting GC, i.e. PyPy. This implies: - changing opener(...).read() calls to opener.read(...) - changing opener(...).write() calls to opener.write(...) - changing open(...).read(...) to util.readfile(...) - changing open(...).write(...) to util.writefile(...)