0.11

• breaking: remove deprecated path handlers based on scanf

• breaking: more getter/setters for request/response, change signatures,
  make request/response private aliases

• fix: release semaphore in case of exception in accept

• feat: add a notion of Middleware

• feat: add ?middlewares param to create

• feat: add ?get_time_s param to create

• feat: close connection if response's headers contains connection

• feat: store start_time in request

• feat: implement connection timeout using socket options
  Default is max_keep_alive = -1.0 which preserves the original behaviour.

• feat: in server-sent-events, add a close() function

• refactor(zip): compression is now a middleware

• perf: pass buf_size in many places, set default buf_size to 16kb

• example: update echo to provide a /stats/ endpoint using a middleware