significant upgrade to selftest, added echotest, better checks for data in queue before socket closure

ext/picotcp/stack/pico_socket.c

@@ -1996,7 +1996,7 @@ int pico_transport_process_in(struct pico_protocol *self, struct pico_frame *f)
         return ret;
 
     if (!IS_BCAST(f)) {
-        dbg("Socket not found... \n");
+        DEBUG_EXTRA("Socket not found...");
         pico_notify_socket_unreachable(f);
         ret = -1;
         pico_err = PICO_ERR_ENOENT;

ext/picotcp/stack/pico_stack.c

@@ -33,6 +33,8 @@
 #include "pico_socket.h"
 #include "heap.h"
 
+#include "../../../include/Debug.hpp"
+
 /* Mockables */
 #if defined UNIT_TEST
 #   define MOCKABLE __attribute__((weak))
@@ -831,13 +833,13 @@ pico_timer_ref_add(pico_time expire, struct pico_timer *t, uint32_t id, uint32_t
     tref.hash = hash;
 
     if (heap_insert(Timers, &tref) < 0) {
-        dbg("Error: failed to insert timer(ID %u) into heap\n", id);
+        DEBUG_ERROR("Error: failed to insert timer(ID %u) into heap", id);
         PICO_FREE(t);
         pico_err = PICO_ERR_ENOMEM;
         return 0;
     }
     if (Timers->n > PICO_MAX_TIMERS) {
-        dbg("Warning: I have %d timers\n", (int)Timers->n);
+        DEBUG_ERROR("Warning: I have %d timers", (int)Timers->n);
     }
 
     return tref.id;