- Added two variables to call to dialog_menu() to save the position 
  in the menu when choosing a menu-option.

- Added dialog_fselect(), implements a fileselector dialog
- Added ui-interface objects: Stringobject, Listobject and Buttonobject.
  The fileselector dialog was built using these objects.
- changed dialog_menu to use PGUP and PGDN
- Added dialog_mesgbox, which display text given in a char buffer.
-