No frameset dropping until GUI

Do not drop any framesets, even if incomplete, until the final stage in the GUI which can then optionally do so. This helps with video decode efficiency and keeps everything moving smoothly in the presence of frame drops on video nodes. Rendering incomplete frames obviously results in flashing.

There are some other fixes in this merge that may relate to random GUI crashes.

applications/gui/src/camera.cpp

@@ -140,7 +140,10 @@ void ftl::gui::Camera::draw(std::vector<ftl::rgbd::FrameSet*> &fss) {
 			ftl::rgbd::Frame *frame = nullptr;
 
 			if ((size_t)fid_ >= fs->frames.size()) return;
+			if (!fs->hasFrame(fid_)) return;
+
 			frame = &fs->frames[fid_];
+			if (!frame->hasChannel(channel_)) return;
 
 			auto &buf = colouriser_->colourise(*frame, channel_, 0);
 
@@ -389,7 +392,8 @@ void ftl::gui::Camera::_draw(std::vector<ftl::rgbd::FrameSet*> &fss) {
 		auto &f = fs2.frames.emplace_back();
 		fs2.count = 1;
 		fs2.mask = 1;
-		fs2.stale = false;
+		//fs2.stale = false;
+		fs2.set(ftl::data::FSFlag::STALE);
 		frame_.swapTo(Channels<0>(Channel::Colour), f);  // Channel::Colour + Channel::Depth
 		fs2.timestamp = ftl::timer::get_time();
 		fs2.id = 0;