changed availability options to include "unset"

Additions:
- item availability "unset" (with localization)

Changes:
- item availability "none" -> "nowhere"

Fixes:
- fixed wrong default item availability in template.json

src/template.json

@@ -46,7 +46,7 @@
             "physical": {
                 "quantity": 1,
                 "price": 0,
-                "availability": "-",
+                "availability": "unset",
                 "storageLocation": "-"
             },
             "equipable": {