Fix incorrect maximum number of chunks per packet

The maximum number of chunks per packet is limited to 255 due to the value being packed into 1 byte in the chunk header. The incorrect limit caused full packets to be packed with the number of chunks value being 0 due to the value 256 overflowing, which would result in receivers not unpacking any chunks due to the number being 0.

Author: Robyt3

src/engine/shared/network.h

@@ -83,7 +83,7 @@ enum
 	NET_PACKETFLAG_COMPRESSION=4,
 	NET_PACKETFLAG_CONNLESS=8,
 
-	NET_MAX_PACKET_CHUNKS=256,
+	NET_MAX_PACKET_CHUNKS = 0xFF,
 
 	// token
 	NET_SEEDTIME = 16,