arp: renamed GlobalARP to GenericARP
arp: IARPCache be more general

- uses Address (instead of IPv4Address) in Notification, renamed it to l3Address from ipv4Address
- added signal ID members
Merged IARPCache to IARP
renamed arpCacheModule parameters to arpModule
added GlobalARP
uses IARP in IPv4NetworkLayer
uses arpType="GlobalARP" instead of ARP.globalARP=true
removed GlobalArpCache from ARP
GenericARP - GenericNetworkProtocol connections let be same as ARP - IPv4 connections
--GenericARP - GenericNetworkProtocol connections let be same as ARP - IPv4 connections - fingerprints changed
IARP: renamed resolveMACAddress() to resolveL3Address()
applications: added common copyright headers.
DHCP: data members are grouped together according to their role (state, parameter, statistic)
SCTPApplications: code refactoring

- added TODOs
- renamings
- improved readability in the class declaratation
SCTPApplications: uint32, uint64, int32, etc. replaced with their corresponding C++ types.
SCTPApplications: removed some unused functions.
SCTPApplications: fixed a memory leak issue and uninitialised msg pointers.
SCTPApplications: removed a lot of explicit type-casts.
SCTPApplications: cosmetics
SCTPApplications: memory deallocation was simplified and moved to the destructor