Prevent nil current_request

Seeing a lot of:

```
NoMethodError: undefined method `handle_response' for nil:NilClass
```

So catching that scenario.
Remove duplicated comment.
Add SocketMixin for de/optimization per-server.
Additional clarity on optimizations possible
De/optimize at start and shutdown; style tweaks, and added SocketMixin
Deoptimize before close
Change to TODO versus implied TODO
Stylistic tweaks, and reshuffled including location to extend self ( for SocketMixin )
Style tweaks, and reshuffled at inclusion point to extend self
SocketMixin module extends self
.is_a? TCPSocket vs. TCPSocket ===
Splitting out servers
Refactor servers into one foundation and three protocols.
Finish refactor of Server #120 and retrofit of SocketMixin #114
Space made
Update usage examples, references in docs, and limited tests.
Minor change to verbiage.
Trim down SocketMixin and make style changes per request
Abandon SocketMixin
remove SocketMixin and bring in #optimize instead, then use it.