Non-strict subscribe/unsubscribe

• WebSocket::subscribe and unsubscribe now takes bool nonStrict as a very significant optimization in certain use cases.
• idleTimeout must be specified as 0 or greater than 8 and is now unsigned short, limiting maximum timeout as 18 hours (2^16 seconds).
• Timeouts are now truncated to nearest 4 second and a warning is displayed for timeouts not being a multiple of 4.
• Timeouts have been micro optimized and will require up to 40% less CPU-time overall (although 40% of nothing is nothing!).