Set inboxServerPermission to manageMessages by default

With single server setups being extremely common, this is a safer
default than not requiring any permissions at all.

src/data/cfg.jsdoc.js

@@ -18,7 +18,7 @@
  * @property {string} [mentionRole="here"]
  * @property {boolean} [pingOnBotMention=true]
  * @property {string} [botMentionResponse]
- * @property {array} [inboxServerPermission=[]]
+ * @property {array} [inboxServerPermission=["manageMessages"]]
  * @property {boolean} [alwaysReply=false]
  * @property {boolean} [alwaysReplyAnon=false]
  * @property {boolean} [useNicknames=false]

src/data/cfg.schema.json

@@ -115,7 +115,7 @@
 
     "inboxServerPermission": {
       "$ref": "#/definitions/stringArray",
-      "default": []
+      "default": ["manageMessages"]
     },
     "alwaysReply": {
       "$ref": "#/definitions/customBoolean",