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/args.c

@@ -409,9 +409,7 @@ app_arg (int add_line, struct date *day, long date, int print_note,
           arg_print_date (today);
           print_date = 0;
         }
-      fputs (" * ", stdout);
-      fputs (ev->mesg, stdout);
-      fputs ("\n", stdout);
+      print_event (" * %m\n", today, ev);
       if (print_note && ev->note)
         print_notefile (stdout, ev->note, 2);
     }