Add main business logic of this program

Now we can download torrents like old Python
version does.

go.mod

@@ -4,9 +4,11 @@ go 1.13
 
 require (
 	github.com/PuerkitoBio/goquery v1.5.0
+	github.com/anacrolix/torrent v1.7.1
+	github.com/dustin/go-humanize v1.0.0
+	github.com/kennygrant/sanitize v1.2.4
 	github.com/kirsle/configdir v0.0.0-20170128060238-e45d2f54772f
 	github.com/rs/zerolog v1.15.0
-	github.com/stretchr/testify v1.4.0 // indirect
 	gitlab.com/pztrn/flagger v0.0.0-20190122123836-d429d7149cc9
 	golang.org/x/text v0.3.0
 )