TransportLayer: Moved ITCP, IUDP, ISCTP under contract.
LinkLayer: Moved module interfaces under contract.
LinkLayer: Moved generic WirelessNic under common.
Routing: Moved module interfaces under contract.
NetworkLayer: Moved module interfaces under contract.
LinkLayer: Moved base classes under base.
NetworkLayer: Moved base classes under base.
NetworkLayer: Moved interfaces from common to contract.
Fixed includes after moves.
Eliminated the weird UnimplementedModule and related *_None modules.

Added firstAvailableOrEmpty NED function, and changed submodules to be present conditionally.
.oppfeatures fixes.
Radio: Fixed a few TODOs, and added some comments.
Manual: Fixed renames, commented out TODOs, etc.
Manual: Removed self referencing contents line from table of contents.
Manual: Fixed the horizontal spacing between the number and the title in TOC.
Manual: Added draft conditional.
Radio: Added TODO.
Manual: Fixed more renames.
diffserv: CID 77588, 77637, 77652, 77676, 77878, 77898: uninitialized member variables
diffserv: CID 77725 Structurally dead code