In method get in class Svtplay: index dict streams by number  instead of key for Python 3 compatibility.
In method get in class Svtplay: index dict streams by number
 instead of key for Python 3 compatibility.

In Python 2, dict.keys() returned a list but in Python 3 it returns a dict_keys
instance which is not indexable. Details: http://stackoverflow.com/questions/8953627/python-dictionary-keys-error

This patch should be compatible with both Python 2 and 3.

leakim/svtplay-dl,spaam/svtplay-dl,dalgr/svtplay-dl,spaam/svtplay-dl,dalgr/svtplay-dl,iwconfig/svtplay-dl,OakNinja/svtplay-dl,qnorsten/svtplay-dl,iwconfig/svtplay-dl,selepo/svtplay-dl,selepo/svtplay-dl,qnorsten/svtplay-dl,OakNinja/svtplay-dl,leakim/svtplay-dl,olof/svtplay-dl,OakNinja/svtplay-dl,leakim/svtplay-dl,olof/svtplay-dl