That way it can be reused more easily. This also avoid having to
change the serialization structure for packets, which is a problem as
external sources of packets (via Broccoli) wouldn't have the new
attributes available to send.
Also moving Packet.{h,cc} and Layer2.{h,cc} into iosource/, and
removing header size from properties that packet sources have to
provide, as we can now compute that easily from the link type.
Plus some more cleanup.
* origin/topic/jsiwek/jj-bugs:
Fix incorrect data delivery skips after gap in HTTP Content-Range.
Fix file analysis placement of data after gap in HTTP Content-Range.
Fix issue w/ TCP reassembler not delivering some segments.
Raise http_entity_data in line with data arrival.
Implement file ID caching for MIME_Mail.
BIT-1240: Fix MIME entity file data/gap ordering.
BIT-1240 #closed
BIT-1246 #closed
BIT-1247 #closed
BIT-1248 #closed
