0.12.0: Frontend removal

• Fixed "undefined function getallheaders()" when using FPM. According
  to the documentation, it should exist,
  but reality shows it doesn't. See https://bugs.php.net/bug.php?id=62596
  (@thekid)
• Merged PR #33: Remove frontend handler. This library will cover the
  HTTP basics, while other more advanced usecases should reside in their
  own respective library
  (@thekid)

0.11.0: Handler return values

• Fixed issue #32: Canonicalize URL before matching - @thekid
• Changed handler return type from void to var and ensured anything
  returned from a handler will be returned from routing and filters.
  Implements functionality suggested in #31
  (@thekid)
• Changed web.filters.Invocation's constructor to be more liberal as
  to what it accepts for its routing argument
  (@thekid)

0.10.0: Testing

• Implemented #30: Request::toString(). The output includes method, URI
  and the HTTP headers sent with the request.
  (@thekid)
• Implemented #29: Exposed "TestInput" and "TestOutput" classes in web.io
  package. This way, people wishing to test their filters and handlers can
  easily unittest them.
  (@thekid)

0.9.0: Request rewriting

• Fixed #28: Send "Content-Length: 0" for empty responses - @thekid
• Merged PR #25: Rewrite - @thekid

0.8.3: PHP 7.2 compatiblity

• Fixed PHP 7.2 compatibility - @thekid

0.8.2: Suppress duplicate log messages

• Suppressed PHP CLI server log messages (which are written to STDERR)
  in -m develop since we're writing our own logfile.
  (@thekid)

0.8.1: Headers fix

• Fixed issue #23: Multiple location headers - @thekid

0.8.0: Cookies

• Merged PR #22: Cookie handling - @thekid
• Merged PR #21: Multiple headers - @thekid
• Defaulted server to keep-alive connections - @thekid

0.7.0: Development webserver

• Merged PR #20: Support development webserver (xp web -m develop)
  (@thekid)
• Changed response always to include a Date header as per RFC 2616,
  section 14.18. See issue #19
  (@thekid)

0.6.3: Prevent security problems in error pages

• Prevented possible security problems by escaping error messages
  (@thekid)