listObjects: Cleanup and naming conventions.

- Marker should be escaped outside in handlers.

- Delimiter should be handled outside in handlers.

- Add missing comments and change the function names.

- Handle case of 'maxKeys' when its set to '0', its a valid

  case and should be treated as such.

fs-dirent-fileno.go

@@ -20,6 +20,7 @@ package main
 
 import "syscall"
 
-func skipDirent(dirent *syscall.Dirent) bool {
+// True if dirent is absent in directory.
+func isEmptyDirent(dirent *syscall.Dirent) bool {
 	return dirent.Fileno == 0
 }