project: replaced proxy with pre-cache

Removed proxy task and replaced with a true honest-to-god pre-cache for
footage. This footage is pre-cached to a sequence and therefore 100% ready
for use in it once the task is done.

app/render/backend/opengl/openglworker.cpp

@@ -41,8 +41,7 @@ void OpenGLWorker::TextureToFrame(const QVariant &texture, FramePtr frame, const
 NodeValue OpenGLWorker::FrameToTexture(DecoderPtr decoder, StreamPtr stream, const TimeRange &range) const
 {
   FramePtr frame = decoder->RetrieveVideo(range.in(),
-                                          video_params().divider(),
-                                          render_mode() == RenderMode::kOffline);
+                                          video_params().divider());
 
   NodeValue value;