added FastColoredConsoleTarget

I wrote a new target. It is faster than ColoredConsole, but has fewer features. It is necessary for debugging when you want to display a lot of information to the console without slowing down the program.

In my test, it is 2-3 times faster
```C#
        public async Task LoggerTest(ILogger logger)
        {
            var sw = new Stopwatch();
            Console.WriteLine("Start Logger Test");
            sw.Start();
            var list = new List<Task>();
            for (int i = 0; i < 30; i++)
                list.Add(Task.Factory.StartNew(() =>
                {
                    for (int j = 0; j < 1000; j++)
                        logger.Debug("Thread {0} - ping {1}", Thread.CurrentThread.ManagedThreadId, j);
                    logger.Error("Thread {0} - end", Thread.CurrentThread.ManagedThreadId);
                }));
            await Task.WhenAll(list);
            sw.Stop();
            //Console.ReadKey();
            Console.WriteLine("Elapsed time {0}", sw.ElapsedMilliseconds);
            Console.WriteLine("Stop Logger Test");
        }
```

I do not know what projects to add target, so only add .net4.5. I hope you will take and do the rest.
Sorry for google translate.