New prerelease for v2.0.0

Pre2 realease features:

- Posibility to define (also by drag/drop action) a
desktop file you want instead of entering options
directly in the button-option-dialog.
- Copy/Paste between buttonbar and childs
- Definable Font for button text
- Updated documentation

Fixed:

- set a default input box (if available) on the
%s askdialogs