0.18

CHANGES:

• add optional middlewares to tiny_httpd_ws

• add Head_middleware.trivial

• add Head_middleware.t; accept it for SSE/websocket

• add Request.pp_with which is a customizable printer

• expose Response.Bad_req

• use iostream for IOs

• add a hmap-typed field to requests, to carry request specific data
  across middlewares

• http_of_dir: ability to setup socket timeout

• add tiny_httpd.ws, a websocket library

• add Response_code.is_success

• fix: No setting of sigprocmask on Windows

• fix: give the correct code+error if protocol upgrade fails

• remove potentially security-leaking debug line

• fix: avoid collisions in Mime_ private module

• fix middlewares: merge-sort per-request middleares and global ones

• fix tiny_httpd dir: handle html files

• perf: optim in read_line

• perf: remove some uses of scanf in parsing

• require iostream-camlzip >= 0.2.1

• add optional dependency on logs

• logs is a testdep for tiny_httpd_camlzip