admin: fix setinterior command spec (#183)

Command /setinterior only accepts a string defined in `interiors.xml` as the 2nd argument. It's not like setElementInterior that only accepts integer.

Author: Lord-Henry

[admin]/admin/conf/commands.xml

@@ -19,7 +19,7 @@
     <command handler="setskin" call="setskin" args="P,i" />
     <command handler="setstat" call="setstat" args="P,i,i" />
     <command handler="setteam" call="setteam" args="P,T" />
-    <command handler="setinterior" call="setinterior" args="P,i" />
+    <command handler="setinterior" call="setinterior" args="P,s" />
     <command handler="setdimension" call="setdimension" args="P,i" />
     <command handler="jetpack" call="jetpack" args="P" />
     <command handler="givevehicle" call="givevehicle" args="P,i" />