ui: move ops reader to ui package

To prepare support for cached OpBlock to refer to other Ops lists.

The exposure of OpsReader is alleviated by the removal of the Refs
and Data accessors for Ops.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/key/queue.go

@@ -11,7 +11,7 @@ type Queue struct {
 	focus    Key
 	events   []Event
 	handlers map[Key]bool
-	reader   ops.Reader
+	reader   ui.OpsReader
 }
 
 type listenerPriority uint8
@@ -25,7 +25,7 @@ const (
 
 func (q *Queue) Frame(root *ui.Ops) TextInputState {
 	q.events = q.events[:0]
-	q.reader.Reset(root.Data(), root.Refs())
+	q.reader.Reset(root)
 	f, pri, hide := resolveFocus(&q.reader, q.focus)
 	changed := f != nil && f != q.focus
 	for k, active := range q.handlers {
@@ -74,7 +74,7 @@ func (q *Queue) For(k Key) []Event {
 	return q.events
 }
 
-func resolveFocus(r *ops.Reader, focus Key) (Key, listenerPriority, bool) {
+func resolveFocus(r *ui.OpsReader, focus Key) (Key, listenerPriority, bool) {
 	var k Key
 	var pri listenerPriority
 	var hide bool