Use a dynamic method to print events to stdout

Add a flexible helper function print_event() and use it whenever we
print events to stdout. This reduces the number of copy-pasted code and
eventually allows for specifying custom format strings.

Following format specifiers are supported:

* 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

@@ -923,6 +923,7 @@ int          shell_exec (int *, int *, char *);
 int          child_wait (int *, int *, int);
 void         press_any_key (void);
 void         print_apoint (const char *, long, struct apoint *);
+void         print_event (const char *, long, struct event *);
 
 /* vars.c */
 extern int               col, row;