* include/grub/net/arp.h: added arp header, arp cache entry and related constants and functions
* net/arp.c: added functions arp_init_table, arp_find_entry, arp_resolve and arp_receive
* net/ethernet.c (send_ethernet_packet): replaced hardcoded hardware address by parameter target_addr
* net/ethernet.c (recv_ethernet_packet): added call to arp_receive when packet is of type 0x803 (ARP) and only return when packet is of type determined by parameter ethertype
* net/ip.c (send_ip_packet): added call to arp_resolve to determine hardware address of destination
* net/netbuff.c (grub_netbuff_alloc): fixed swapped parameters in call to grub_memalign
an to list its information with command ls.
* fs/ieee1275/ofnet.c (grub_ofnet_open): parse parameters to determine netdisk data
* fs/ieee1275/ofnet.c (grub_ofnet_close): dealloc netdisk data
* include/grub/disk.h: added struct grub_netdisk_data
* include/grub/ieee1275/ofnet.h: added newline
* kern/disk.c (grub_disk_open): ignore partition check for netdisk
* normal/misc.c (grub_normal_print_device_info): added support to list netdisk information
