Break the fs package up into smaller parts.

The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.

The new code layout is documented in CONTRIBUTING.

cmd/serve/http/http.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/ncw/rclone/cmd"
 	"github.com/ncw/rclone/fs"
+	"github.com/ncw/rclone/fs/accounting"
 	"github.com/ncw/rclone/lib/rest"
 	"github.com/ncw/rclone/vfs"
 	"github.com/ncw/rclone/vfs/vfsflags"
@@ -159,7 +160,7 @@ type indexData struct {
 
 // error returns an http.StatusInternalServerError and logs the error
 func internalError(what interface{}, w http.ResponseWriter, text string, err error) {
-	fs.Stats.Error(err)
+	fs.CountError(err)
 	fs.Errorf(what, "%s: %v", text, err)
 	http.Error(w, text+".", http.StatusInternalServerError)
 }
@@ -192,8 +193,8 @@ func (s *server) serveDir(w http.ResponseWriter, r *http.Request, dirRemote stri
 	}
 
 	// Account the transfer
-	fs.Stats.Transferring(dirRemote)
-	defer fs.Stats.DoneTransferring(dirRemote, true)
+	accounting.Stats.Transferring(dirRemote)
+	defer accounting.Stats.DoneTransferring(dirRemote, true)
 
 	fs.Infof(dirRemote, "%s: Serving directory", r.RemoteAddr)
 	err = indexTemplate.Execute(w, indexData{
@@ -259,8 +260,8 @@ func (s *server) serveFile(w http.ResponseWriter, r *http.Request, remote string
 	}()
 
 	// Account the transfer
-	fs.Stats.Transferring(remote)
-	defer fs.Stats.DoneTransferring(remote, true)
+	accounting.Stats.Transferring(remote)
+	defer accounting.Stats.DoneTransferring(remote, true)
 	// FIXME in = fs.NewAccount(in, obj).WithBuffer() // account the transfer
 
 	// Serve the file