Initialize linked list for recurrent items

When switching to the generic linked list implementation for recurring
events in 9fab248 (Use generic lists for recurring apointments and
events., 2011-04-16), no initialization routine for the list of
recurring events was added. Fix this and properly initialize the list on
startup.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>
Add a key binding to reload appointments and todos

This allows for reloading the appointment and todo item files without
having to restart calcurse.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>
Automatically select first item in list boxes

If the selection is empty during listbox_load_items() and there is at
least one item in the list, automatically select the first item.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>