Custom CleanroomLogger Channel demo

Log+Extension.swift

Original issues : [CleanroomLogger/issues/37](https://github.com/emaloney/CleanroomLogger/issues/37)

    extension Log {
        static func setup() {
            #if DEBUG
                Log.enable(debugMode: true)
                Log.sqlite = MyLogChannel(prefix: "Sqlite") // enable your channel or using Xcode console filter
            #endif
        }
    }

    extension Log {

        // Adapter Class
        class MyLogChannel{
            let prefix:String
            init(prefix:String) {
                self.prefix = prefix
            }
            func info(_ msg: String?, function: String = #function, filePath: String = #file, fileLine: Int = #line) {
                guard let msg = msg else {return}
                Log.info?.message(prefix + " : " + msg, function: function, filePath: filePath, fileLine: fileLine)
            }
        }

        static var sqlite:MyLogChannel?
    }

Usage.swift

      Log.sqlite.info("666")

      or
      declare a global const `LogSqlite`
      let LogSqlite = Log.sqlite
      LogSqlite.info("hehe")