add stacktrace, improve assert, improve debugbreak

src/core/core.c

@@ -9,6 +9,9 @@
     #include <string.h>
     #include <stdio.h>
     #include <stdlib.h>
+    #include <signal.h>
+    #define B_STACKTRACE_IMPL
+    #include "stacktrace.h"
     #include "core_platform_win32.c"
 #else
     #include <math.h>
@@ -17,6 +20,12 @@
     #include <stdlib.h>
     #include <time.h>
     #include <sys/mman.h>
+    #include <signal.h>
+
+    #define B_STACKTRACE_IMPL
+    #include "stacktrace.h"
+//:unix_debug_break
+//static void os_unix_sigtrap(int signum) { signal(SIGTRAP, SIG_DFL); }
     #include "core_platform_unix.c"
 #endif