Use a dynamic method to print todo items to stdout

This goes in line with the other commits adding print_*() support.

Following format specifiers are allowed:

* p: Print the priority of the item
* m: Print the description of the item
* n: Print the name of the note file belonging to the item

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

src/calcurse.h

@@ -926,6 +926,7 @@ void         print_event (const char *, long, struct event *);
 void         print_recur_apoint (const char *, long, unsigned,
                                  struct recur_apoint *);
 void         print_recur_event (const char *, long, struct recur_event *);
+void         print_todo (const char *, struct todo *);
 
 /* vars.c */
 extern int               col, row;