Moved from guint to gint to match libical internal data.

The internal attributes of both widgets were guint types, but
since libical library has those values (day,month,hour) as int
inside icaltimetype struct, I decided t move to gint in order to
avoid compiler warnings, and ugly hidden things.

src/gcal-date-entry.h

@@ -55,14 +55,14 @@ GType            gcal_date_entry_get_type        (void);
 GtkWidget*       gcal_date_entry_new             (void);
 
 void             gcal_date_entry_set_date        (GcalDateEntry *entry,
-                                                  guint          day,
-                                                  guint          month,
-                                                  guint          year);
+                                                  gint           day,
+                                                  gint           month,
+                                                  gint           year);
 
 void             gcal_date_entry_get_date        (GcalDateEntry *entry,
-                                                  guint         *day,
-                                                  guint         *month,
-                                                  guint         *year);
+                                                  gint          *day,
+                                                  gint          *month,
+                                                  gint          *year);
 
 G_END_DECLS