Protect against java versioning

- Cast ByteBuffers to Buffer before calling #rewind or #flip

src/main/java/com/jozufozu/flywheel/backend/ShaderSources.java

@@ -5,6 +5,7 @@ import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.StringReader;
+import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.channels.Channels;
 import java.nio.channels.FileChannel;
@@ -182,7 +183,7 @@ public class ShaderSources implements ISelectiveResourceReloadListener {
 		try {
 			bytebuffer = readToBuffer(is);
 			int i = bytebuffer.position();
-			bytebuffer.rewind();
+			((Buffer) bytebuffer).rewind();
 			return MemoryUtil.memASCII(bytebuffer, i);
 		} catch (IOException e) {
 

src/main/java/com/jozufozu/flywheel/backend/gl/buffer/VecBuffer.java

@@ -1,5 +1,6 @@
 package com.jozufozu.flywheel.backend.gl.buffer;
 
+import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 
@@ -29,7 +30,7 @@ public class VecBuffer {
 	}
 
 	public VecBuffer rewind() {
-		internal.rewind();
+		((Buffer) internal).rewind();
 
 		return this;
 	}

src/main/java/com/jozufozu/flywheel/backend/instancing/InstanceMaterial.java

@@ -1,5 +1,6 @@
 package com.jozufozu.flywheel.backend.instancing;
 
+import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.Arrays;
@@ -137,7 +138,7 @@ public class InstanceMaterial<D extends InstanceData> {
 			vertices.putFloat(reader.getV(i));
 		}
 
-		vertices.rewind();
+		((Buffer) vertices).rewind();
 
 		// return new BufferedModel(GlPrimitive.QUADS, format, vertices, vertexCount);
 

src/main/java/com/jozufozu/flywheel/core/QuadConverter.java

@@ -1,5 +1,6 @@
 package com.jozufozu.flywheel.core;
 
+import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.EnumMap;
@@ -136,7 +137,7 @@ public class QuadConverter {
 			type.castAndBuffer(indices, i + 2);
 			type.castAndBuffer(indices, i + 3);
 		}
-		indices.flip();
+		((Buffer) indices).flip();
 	}
 
 	private GlBuffer getBuffer(GlNumericType type) {