[core] add INI file/portable support

* Application will start in portable mode if its name contains a 'p'
  eg. "rufus_portable.exe" or "prufus.exe"
* Closes #264
* Also fix a couple smaller issues

src/stdfn.c

@@ -27,6 +27,7 @@
 #include "msapi_utf8.h"
 #include "rufus.h"
 #include "resource.h"
+#include "settings.h"
 #include "localization.h"
 
 int  nWindowsVersion = WINDOWS_UNDEFINED;