Apply the style rule that an accessor is named similar to the the underlying
value. Provide read and write accessors for each mandatory header attribute.
Fix some incorrect structure in the headers like with the flags field
in Ipv4_packet.
Ref #2490
Encapsulate the enum into a struct so that it is named
Ethernet_frame::Type::Enum, give it the correct storage type
uint16_t, and remove those values that are (AFAIK) not used by
now (genode, world).
Ref #2490
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082