fixed a (mainly) garbage-cleanup/tmpfile bug

previously, i think it was converting a tmpfile() FILE HANDLE to a string, resulting in string("1337") (on OSs where file handles are integers anyway, like all OSs i know), then creating a file called 1337 , and using that as a cookiejar for curl.. problem is, this isn't automatically removed on script end :o

now we're actually telling curl to use the file created by tmpfile() as a cookiejar; this file will be deleted automatically on script end ^^