Implement ffmpeg-independent PNGWriter (closes #476)

Creates a dedicated folder for each video and does not depend on ffmpeg, just
like the EXRWriter (but supporting all MC versions).

Also does 32 bit depth export by chunking the 32-bit float into the 8-bit BGRA
component channels.

src/main/java/com/replaymod/render/PNGWriter.java

@@ -0,0 +1,71 @@
+package com.replaymod.render;
+
+import com.replaymod.core.versions.MCVer;
+import com.replaymod.render.blend.Util.IOConsumer;
+import com.replaymod.render.frame.BitmapFrame;
+import com.replaymod.render.rendering.Channel;
+import com.replaymod.render.rendering.FrameConsumer;
+import com.replaymod.render.utils.ByteBufferPool;
+import de.johni0702.minecraft.gui.utils.lwjgl.ReadableDimension;
+import de.johni0702.minecraft.gui.versions.Image;
+import net.minecraft.util.crash.CrashReport;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Map;
+
+public class PNGWriter implements FrameConsumer<BitmapFrame> {
+
+    private final Path outputFolder;
+
+    public PNGWriter(Path outputFolder) throws IOException {
+        this.outputFolder = outputFolder;
+
+        Files.createDirectories(outputFolder);
+    }
+
+    @Override
+    public void consume(Map<Channel, BitmapFrame> channels) {
+        BitmapFrame bgraFrame = channels.get(Channel.BRGA);
+        BitmapFrame depthFrame = channels.get(Channel.DEPTH);
+        try {
+            if (bgraFrame != null) {
+                withImage(bgraFrame, image ->
+                        image.writePNG(outputFolder.resolve(bgraFrame.getFrameId() + ".png").toFile()));
+            }
+            if (depthFrame != null) {
+                withImage(depthFrame, image ->
+                        image.writePNG(outputFolder.resolve(depthFrame.getFrameId() + ".depth.png").toFile()));
+            }
+        } catch (Throwable t) {
+            MCVer.getMinecraft().setCrashReport(CrashReport.create(t, "Exporting EXR frame"));
+        } finally {
+            channels.values().forEach(it -> ByteBufferPool.release(it.getByteBuffer()));
+        }
+    }
+
+    private void withImage(BitmapFrame frame, IOConsumer<Image> consumer) throws IOException {
+        ByteBuffer buffer = frame.getByteBuffer();
+        ReadableDimension size = frame.getSize();
+        int width = size.getWidth();
+        int height = size.getHeight();
+        try (Image image = new Image(width, height)) {
+            for (int y = 0; y < height; y++) {
+                for (int x = 0; x < width; x++) {
+                    byte b = buffer.get();
+                    byte g = buffer.get();
+                    byte r = buffer.get();
+                    byte a = buffer.get();
+                    image.setRGBA(x, y, r, g, b, a);
+                }
+            }
+            consumer.accept(image);
+        }
+    }
+
+    @Override
+    public void close() {
+    }
+}