Introduce MaxHeaderSize for respose reader. Bump to go1.17

update to use go 1.16

Fix write lock deadline handling (#7)

## Issue

The existing code in go-algorand is using two go-routines for reading/writing and a separate go-routine for opening/closing the connections.
When a client connection becomes non-responsive ( i.e. the writer is not returning ), the current implementation tries to close the connection. However, per WebSocket specification, the client is supposed to send a Close message first.

The close message is being sent using the `WriteControl` method, which is supposed to be able to run concurrently with `WriteMessage`. However, both reaches `Conn.write` where it attempt to acquire a writing lock.

Since the `WriteMessage -> Conn.write` is stuck ( but the `WriteControl` doesn't really know it's stuck indefinitely ), the `WriteControl -> Conn.write` get blocks indefinitely as well.

Unlike the `WriteMessage`, when calling `WriteControl`, we provide a deadline : a timestamp after which we don't care if the message was actually sent. In this PR, I have added handling that would limit the time the `Conn.write` would wait to that deadline. 

From spec perspective, it would be a violation of the WebSocket protocol; however, given that the other party is no longer responsive, a successful writing of a Close message is not possible, it would probably be just fine.

Merge pull request #6 from algorand/tsachi/properclose

flush the connection when writing control messages

Merge pull request #4 from algorand/tsachi/fixleakygoroutine

Fix a leaky go-routine on server side connections

Merge pull request #3 from algobolson/WriteControl_fix

Fix Conn.WriteControl() to use the same underlying Conn.write() as regular messages so that it does buffering properly.
Add tests that WriteControl() and WriteMessage() can both correctly send a CloseMessage

Move context to first parameter in DialContext

Follows best practice and pkg/context documentation:

> The Context should be the first parameter, typically named ctx

Improve server subprotocol documentation

Partial fix for 404.

Reduce memory used in chat example

pool flate writers