Added key exchange to LAIKA_HANDSHAKE_*

- test keys are defined in laika.h
- bug fixes & refactoring with laikaM_growarray()

cnc/include/cnc.h

@@ -8,6 +8,7 @@
 #include "lpeer.h"
 
 struct sLaika_cnc {
+    uint8_t priv[crypto_box_SECRETKEYBYTES], pub[crypto_box_PUBLICKEYBYTES];
     struct sLaika_socket sock;
     struct sLaika_pollList pList;
 };