update RTorrent compatibility for 0.9.x
This patch is required for 0.9.7 which has been out for 17 months. 0.9.6 is more than 4 years old now. I suspect it'll work with 0.9.6 still and the old get_ methods were just finally deprecated in .7...
This takes compatibility requirements up from 0.8.1 to 0.9.0. 0.8.x is at least 8 years old.
I cannot easily test with 0.9.6, but I'm open to it if necessary.