Added Channel model and API for it

schema/types/channel.graphql

@@ -0,0 +1,51 @@
+# Information about an IRC channel
+type Channel {
+  # The channel's name
+  name: String!
+
+  # Whether the channel should be logged
+  logged: Boolean!
+
+  # Whether the channel is a hub channel
+  hub: Boolean!
+
+  # The event name, or `null` if none is specified
+  eventName: String
+
+  # The location name, or `null` if none is specified
+  locationName: String
+}
+
+input ChannelAddInput {
+  # The channel's name
+  name: String!
+  
+  # Whether the channel should be logged
+  logged: Boolean
+
+  # Whether the channel is a hub channel
+  hub: Boolean
+
+  # The event name, or `null` if none is specified
+  eventName: String
+
+  # The location name, or `null` if none is specified
+  locationName: String
+}
+
+input ChannelEditInput {
+  # The channel's name
+  name: String!
+  
+  # Whether the channel should be logged
+  logged: Boolean
+
+  # Whether the channel is a hub channel
+  hub: Boolean
+
+  # The event name, or `null` if none is specified
+  eventName: String
+
+  # The location name, or `null` if none is specified
+  locationName: String
+}