WebSocket++/0.4.0

• BREAKING API CHANGE: All WebSocket++ methods now throw an exception of type
  websocketpp::exception which derives from std::exception. This normalizes
  all exception types under the standard exception hierarchy and allows
  WebSocket++ exceptions to be caught in the same statement as others. The error
  code that was previously thrown is wrapped in the exception object and can be
  accessed via the websocketpp::exception::code() method.
• BREAKING API CHANGE: Custom logging policies have some new required
  constructors that take generic config settings rather than pointers to
  std::ostreams. This allows writing logging policies that do not involve the
  use of std::ostream. This does not affect anyone using the built in logging
  policies.
• BREAKING UTILITY CHANGE: websocketpp::lib::net::htonll and
  websocketpp::lib::net::ntohll have been prefixed with an underscore to avoid
  conflicts with similarly named macros in some operating systems. If you are
  using the WebSocket++ provided 64 bit host/network byte order functions you
  will need to switch to the prefixed versions.
• BREAKING UTILITY CHANGE: The signature of base64_encode has changed from
  websocketpp::base64_encode(unsigned char const *, unsigned int) to
  websocketpp::base64_encode(unsigned char const *, size_t).
• BREAKING UTILITY CHANGE: The signature of sha1::calc has changed from
  websocketpp::sha1::calc(void const *, int, unsigned char *) to
  websocketpp::sha1::calc(void const *, size_t, unsigned char *)
• Feature: Adds incomplete minimal_server and minimal_client configs that
  can be used to build custom configs without pulling in the dependencies of
  core or core_client. These configs will offer a stable base config to
  future-proof custom configs.
• Improvement: Core library no longer has std::iostream as a dependency.
  std::iostream is still required for the optional iostream logging policy and
  iostream transport.
• Bug: C++11 Chrono support was being incorrectly detected by the boost_config
  header. Thank you Max Dmitrichenko for reporting and a patch.
• Bug: use of std::put_time is now guarded by a unique flag rather than a
  chrono library flag. Thank you Max Dmitrichenko for reporting.
• Bug: Fixes non-thread safe use of std::localtime. #347 #383
• Compatibility: Adjust usage of std::min to be more compatible with systems
  that define a min(...) macro.
• Compatibility: Removes unused parameters from all library, test, and example
  code. This assists with those developing with -Werror and -Wunused-parameter
  #376
• Compatibility: Renames ntohll and htonll methods to avoid conflicts with
  platform specific macros. #358 #381, #382 Thank you logotype, unphased,
  svendjo
• Cleanup: Removes unused functions, fixes variable shadow warnings, normalizes
  all whitespace in library, examples, and tests to 4 spaces. #376