#3 Calendar: Add an option dialog

[Gerhard W. Gruber]

Add an option dialog where the user can store some
default options like:
Monday or Sunday first day of Week
Enable debug info
Automatically save size of dialog and columns.
Edit the order of events in the grid (i.e. Bills first)
Show a messagebox also for billevents (or make it an
additional option).
Colours
Fonts