Fix: Ignore excessive whitespace in chunk header for Transfer-Encoding: chunked (#123 by @DangerLifter and @clue)

Fix: Ignore invalid incoming Transfer-Encoding response header (#122 by @clue)

Improve documentation for Client (and advanced Connector) (#111 by @jsor and #121 by @clue)

Improve test suite by adding support for PHPUnit 6 (#112 by @carusogabriel)