Add "name" field to struct device to allow human-readable hardware device

names.

Add "dev" pointer in struct net_device to tie network interfaces back to a
hardware device.

Force natural alignment of data types in __table() macros.  This seems to
prevent gcc from taking the unilateral decision to occasionally increase
their alignment (which screws up the table packing).

src/include/gpxe/command.h

@@ -17,6 +17,6 @@ struct command {
 	int ( * exec ) ( int argc, char **argv );
 };
 
-#define __command __table ( commands, 01 )
+#define __command __table ( struct command, commands, 01 )
 
 #endif /* _GPXE_COMMAND_H */