Demo: Fixed malloc/free mismatch and leak when destructing demo console (if it has been used) (#536)

imgui_demo.cpp

@@ -1890,14 +1890,14 @@ struct ExampleAppConsole
     ~ExampleAppConsole()
     {
         ClearLog();
-        for (int i = 0; i < Items.Size; i++)
+        for (int i = 0; i < History.Size; i++)
             free(History[i]);
     }
 
     // Portable helpers
     static int   Stricmp(const char* str1, const char* str2)         { int d; while ((d = toupper(*str2) - toupper(*str1)) == 0 && *str1) { str1++; str2++; } return d; }
     static int   Strnicmp(const char* str1, const char* str2, int n) { int d = 0; while (n > 0 && (d = toupper(*str2) - toupper(*str1)) == 0 && *str1) { str1++; str2++; n--; } return d; }
-    static char* Strdup(const char *str)                             { size_t len = strlen(str) + 1; void* buff = ImGui::MemAlloc(len); return (char*)memcpy(buff, (const void*)str, len); }
+    static char* Strdup(const char *str)                             { size_t len = strlen(str) + 1; void* buff = malloc(len); return (char*)memcpy(buff, (const void*)str, len); }
 
     void    ClearLog()
     {