reduce item.h include dependencies

src/kernel/alliance.c

@@ -23,7 +23,6 @@ without prior permission by the authors of Eressea.
 #include <kernel/order.h>
 #include <kernel/region.h>
 #include <kernel/unit.h>
-#include <kernel/item.h>
 #include <kernel/command.h>
 
 /* util includes */

src/kernel/skills.c

@@ -21,7 +21,6 @@ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #include "skill.h"
 
 #include "curse.h"
-#include "item.h"
 #include "race.h"
 #include "region.h"
 #include "terrain.h"