IPv4/IPv6: renamed IPvXAddress to Address, RoutingTable to IPv4RoutingTable, etc.

IPvXAddress          -> Address
IPvXAddressResolver  -> AddressResolver
IRoutingTable        -> IIPv4RoutingTable
RoutingTable         -> IPv4RoutingTable
RoutingTable6        -> IPv6RoutingTable
RoutingTableAccess   -> IPv4RoutingTableAccess
IPv4/IPv6: dynamic registration of upper layer protocols; merge IPv?NetworkLayer's transport gates

TCP, UDP, SCTP, RSVP, OSPF, MANET are all merged into transport gates.
Network user modules must register their protocol number by sending
an IPRegisterProtocolCommand from initialize.

Introduced an IPSocket class that wraps the registration process.
===ignore RegisterProtocol messages in fingerprint calculation
---fixed handling of unregistered protocols, for: IPv4/IPv6: dynamic registration of upper layer protocols; merge IPv?NetworkLayer's transport gates
--- fixed Manet for: IPv4/IPv6: dynamic registration of upper layer protocols; merge IPv?NetworkLayer's transport gates
=== added RegisterProtocol messages to fingerprints
IPv4/IPv6: rename and move NetworkLayer and NetworkLayer6

- NetworkLayer was renamed to IPv4NetworkLayer and moved into src/networklayer/ipv4
- similar change for IPv6

Conflicts:
	src/nodes/inet/NodeBase.ned
	src/nodes/mpls/LDP_LSR.ned
	src/nodes/mpls/RSVP_LSR.ned
	src/transport/rtp/RTPHost.ned
ARP: minor code cleanup
ARP: factored out an IARPCache
PacketDump: added ARP
+++Removed routingFile parameter of IPv4 nodes (NodeBase, InternetCloud, LDP_LSR, RSVP_LSR)
+++NodeBase: IPForward and forwardMulticast parameter
fixes for ARP: fixed getDirectAddressResolution() and getInverseAddressResolution() funcitons

pending test and expiry test was missed
ARP: refactoring: ARP is now next to the IPv4 module not below it; see TODO below!

Motivation:
 - performance improvement (datagrams no longer go through ARP)
 - conceptually better (packets to PPP no longer flow through ARP)
 - more consistent with how IPv6 and NeighbourDiscovery are organized

TODO:
 - update NED docu of both ARP and IPv4!
 - proxyARP is now both in IPv4 and ARP??
 - refactor ARP gates: netwIn/netwOut/arpResIn (all connecting to IPv4 though)
 - note: IPv4RoutingDecision is now only effectively used on the ip-->arp connection
--- ARP: disable fingerprint tests related by InternetCloud (runtime error)

should be refactoring InternetCloud for refactored ARP
-- IPv4/ARP: IPv4 module processing msgs from ARP without processing delay
~~ ARP fingerprints changed

tested the scalar outputs
2 examples differs only:
    dhcp/eth/omnetpp.ini -c General, 5000s
    ospfv2/fulltest/omnetpp.ini -c General, 100s
ARP, IPv4: introduce/rename proxyARP parameter
InternetCloud: useProxyARP,respondToProxyARP
IPv4NetworkLayer: always turn on useProxyARP, otherwise many existing simulations break

Setting useProxyARP=false breaks about 31 smoke test cases with:
"Cannot send datagram on broadcast interface: no next-hop address and Proxy ARP is disabled."

Cause: IPv4Configurator often doesn't fill in the next-hop address in the routes!