first commit with streaming support (buggy and unreliable)

rbcs-common/src/main/kotlin/net/woggioni/rbcs/common/BB.kt

@@ -0,0 +1,15 @@
+package net.woggioni.rbcs.common
+
+import io.netty.buffer.ByteBuf
+import io.netty.buffer.ByteBufAllocator
+import io.netty.buffer.CompositeByteBuf
+
+fun extractChunk(buf: CompositeByteBuf, alloc: ByteBufAllocator): ByteBuf {
+    val chunk = alloc.compositeBuffer()
+    for (component in buf.decompose(0, buf.readableBytes())) {
+        chunk.addComponent(true, component.retain())
+    }
+    buf.removeComponents(0, buf.numComponents())
+    buf.clear()
+    return chunk
+}