opt: video subtitle

avoid refetching subtitle
fix stuck when parsing large subtitle body

opt: viewpoints

Update README.md

Signed-off-by: bggRGjQaUbCoE <githubaccount56556@proton.me>

lib/plugin/pl_player/models/bottom_control_type.dart

@@ -10,4 +10,5 @@ enum BottomControlType {
   speed,
   fullscreen,
   custom,
+  viewPoints,
 }