Misc improvements (#347)

* - Allow for items without namespaces in loot tables

* - Made rolls in loot table required

* - Account for match tag conditions by not requiring item and count

* - Allow forward / in feature (and rule) identifers

* - Added pattern for structure names

* - Change atlas > texture_name to const

* - Allow . in texture entries in atlas files

* - Food nutrition can only be ints

source/general/feature/identifier.json

@@ -2,7 +2,7 @@
   "$id": "blockception.minecraft.feature.identifier",
   "description": "A minecraft feature identifier.",
   "examples": ["namespace:feature"],
-  "pattern": "^[0-9a-zA-Z:_\\.\\-]+$",
+  "pattern": "^[0-9a-zA-Z:_\\.\/-]+$",
   "title": "Feature Identifier",
   "type": "string",
   "defaultSnippets": [{ "label": "New Identifier", "body": "$1:$2" }]