cryptonote_core does not depend on p2p anymore

As a followon side effect, this makes a lot of inline code
included only in particular cpp files (and instanciated
when necessary.

src/rpc/core_rpc_server.cpp

@@ -44,6 +44,8 @@ using namespace epee;
 #include "crypto/hash.h"
 #include "rpc/rpc_args.h"
 #include "core_rpc_server_error_codes.h"
+#include "p2p/net_node.h"
+#include "version.h"
 
 #undef MONERO_DEFAULT_LOG_CATEGORY
 #define MONERO_DEFAULT_LOG_CATEGORY "daemon.rpc"