Determine when to apply autoscroll

When shrinking the window, scrolling was limited to only the current
view buffer. This should implement auto-scrolling. It's a little bit
janky, but should be sufficient for now.

controller/controller.go

@@ -1,17 +1,15 @@
 package controller
 
 import (
-	"time"
-
 	config "github.com/davegallant/srv/config"
 	feeds "github.com/davegallant/srv/feeds"
 )
 
 // Controller keeps everything together
 type Controller struct {
-	Config     config.Configuration
-	lastUpdate time.Time
-	Rss        *feeds.RSS
+	Config      config.Configuration
+	Rss         *feeds.RSS
+	CurrentFeed int
 }
 
 // Init initiates the controller with config
@@ -19,4 +17,5 @@ func (c *Controller) Init(conf string) {
 	c.Config = config.LoadConfiguration(conf)
 	c.Rss = &feeds.RSS{}
 	c.Rss.Update(c.Config.Feeds)
+	c.CurrentFeed = 0
 }