Changes in notifying about new releases.

- Unified preferences settings. version_check option is replaced with notify_release that has 3 states.
- fixed logic when show notification based on version string.
- notification shows released version
- dialog notifying new version is never showing if external updater is running.
Escape quotes inside path to external updater

src/slic3r/GUI/ConfigWizard.cpp

@@ -1206,7 +1206,7 @@ PageUpdate::PageUpdate(ConfigWizard *parent)
     boldfont.SetWeight(wxFONTWEIGHT_BOLD);
 
     auto *box_slic3r = new wxCheckBox(this, wxID_ANY, _L("Check for application updates"));
-    box_slic3r->SetValue(app_config->get("version_check") == "1");
+    box_slic3r->SetValue(app_config->get("notify_release") != "none");
     append(box_slic3r);
     append_text(wxString::Format(_L(
         "If enabled, %s checks for new application versions online. When a new version becomes available, "
@@ -2697,7 +2697,7 @@ bool ConfigWizard::priv::apply_config(AppConfig *app_config, PresetBundle *prese
 
     app_config->set_vendors(appconfig_new);
 
-    app_config->set("version_check", page_update->version_check ? "1" : "0");
+    app_config->set("notify_release", page_update->version_check ? "all" : "none");
     app_config->set("preset_update", page_update->preset_update ? "1" : "0");
     app_config->set("export_sources_full_pathnames", page_reload_from_disk->full_pathnames ? "1" : "0");