rename redis-sharp.cs to RedisComm.cs for common communication parts
put classes Redis and SortOptions into namespace RedisSharp
Separate Redis.cs from RedisComm.cs (former redis-sharp.cs)

- Redis provides a synchronous client
- RedisSub provides a subscriber for pub/sub messaging
- RedisComm implements communication and protocol handling
- use CultureInfo.InvariantCulture for conversion of objects to strings