ZoneCode: Fix XModel bone count not being unsigned but being used as it was

src/ZoneCommon/Game/T6/T6_Assets.h

@@ -550,9 +550,9 @@ namespace T6
     struct XModel
     {
         const char* name;
-        char numBones;
-        char numRootBones;
-        char numsurfs;
+        unsigned char numBones;
+        unsigned char numRootBones;
+        unsigned char numsurfs;
         char lodRampType;
         unsigned __int16* boneNames;
         char* parentList;