Several fixes and improvements in SendSystemInfoDialog:

- do not show memory in MB, show it in GiB rounded to one decimal place
- when sending fails, the HTTP error code is not presented to the user (it is logged though)
- when the user cancels the sending, no extra "sending cancelled" message is shown
- in case there is no internet connection, the dialog is not shown at all
- a 6 second timeout for a case that connection is lost during sending
- the dialog is only shown when the wizard does not show on startup

src/slic3r/GUI/GUI_App.cpp

@@ -676,16 +676,18 @@ void GUI_App::post_init()
     if (this->preset_updater) {
         this->check_updates(false);
         CallAfter([this] {
-            this->config_wizard_startup();
+            bool cw_showed = this->config_wizard_startup();
             this->preset_updater->slic3r_update_notify();
             this->preset_updater->sync(preset_bundle);
+            if (! cw_showed) {
+                // The CallAfter is needed as well, without it, GL extensions did not show.
+                // Also, we only want to show this when the wizard does not, so the new user
+                // sees something else than "we want something" on the first start.
+                show_send_system_info_dialog_if_needed();
+            }
         });
     }
 
-    // 'Send system info' dialog. Again, a CallAfter is needed on mac.
-    // Without it, GL extensions did not show.
-    CallAfter([] { show_send_system_info_dialog_if_needed(); });
-
 #ifdef _WIN32
     // Sets window property to mainframe so other instances can indentify it.
     OtherInstanceMessageHandler::init_windows_properties(mainframe, m_instance_hash_int);