Finished implementing xp shop. It allows users to buy frames and backgrounds if the user enables the feature in data/xp.yml. It can also be available only to patrons

src/NadekoBot/data/strings/responses/responses.en-US.json

@@ -807,6 +807,7 @@
   "xp_role_reward_remove_role": "Users who reach level {0} will lose {1} role.",
   "xp_receive_role": "Receive {0} role.",
   "xp_lose_role": "Lose {0} role.",
+  "xp_shop_disabled": "Xp shop is disabled by the owner, or there are no items for sale.",
   "role_not_found": "Role not found: {0}",
   "cur_reward_cleared": "Reaching level {0} will no longer reward any {1}.",
   "cur_reward_added": "Users who reach level {0} will receive {1}.",
@@ -882,6 +883,10 @@
   "timely_reset": "All users will be able to claim timely currency again.",
   "timely_time": "It's time for your timely reward.",
   "price": "Price",
+  "buy": "Buy",
+  "use": "Use",
+  "in_use": "In use",
+  "xp_shop_item_cant_use": "You can't use this item as it doesn't exist or you don't own it.",
   "market_cap": "Market Cap",
   "market_cap_dominance": "Dominance",
   "circulating_supply": "Circulating Supply",
@@ -994,6 +999,8 @@
   "feature_limit_reached_you": "You've reached the limit of {0} for the {1} feature. You may be able to increase this limit by upgrading your patron tier.",
   "feature_limit_reached_owner": "Server owner has reached the limit of {0} for the {1} feature. Server owner may be able to upgrade this limit by upgrading patron tier.",
   "feature_limit_reached_either": "The limit of {0} for the {1} feature has been reached. Either you or the server owner may able to upgrade this limit by upgrading the patron tier.",
+  "feature_required_tier": "Using this feature requires patron tier {0} or higher.",
+  "available_commands": "Available Commands",
   "tier": "Tier",
   "pledge": "Pledge",
   "expires": "Expires",