Added "Restore window position on start" option to the "Preferences > General"

+ added crash detection for the cases, when PrusaSlicer is started from secondary display

Possible fix for part of:
 #2939 - PrusaSlic3r freezing at startup (Win 10)
and
 #5573 - PrusaSlicer won't launch on secondary monitor. Nahimic?

src/libslic3r/AppConfig.cpp

@@ -175,6 +175,9 @@ void AppConfig::set_defaults()
     if (get("show_splash_screen").empty())
         set("show_splash_screen", "1");
 
+    if (get("restore_win_position").empty())
+        set("restore_win_position", "1");       // allowed values - "1", "0", "crashed_at_..."
+
     if (get("show_hints").empty())
         set("show_hints", "1");