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-time-entry.h

@@ -53,12 +53,12 @@ GType            gcal_time_entry_get_type        (void);
 GtkWidget*       gcal_time_entry_new             (void);
 
 void             gcal_time_entry_set_time        (GcalTimeEntry *entry,
-                                                  guint          hours,
-                                                  guint          minutes);
+                                                  gint           hours,
+                                                  gint           minutes);
 
 void             gcal_time_entry_get_time        (GcalTimeEntry *entry,
-                                                  guint         *hours,
-                                                  guint         *minutes);
+                                                  gint          *hours,
+                                                  gint          *minutes);
 
 G_END_DECLS