XRL 3.0.0

Changes

• New major release due to API breakage.
• To make XRL work on PHP 7, several classes had to be renamed.
  This concerns classes related to XML-RPC types whose names
  clashed with now-reserved PHP names (like "Int", "String", and so on).
  See https://wiki.php.net/rfc/scalar_type_hints_v5#backward_incompatible_changes
  for more background information on this issue.

Fixed bugs

• [#9] Fix compatibility with PHP 7.0+