Support parameter type and return type declarations in PHP 7

[asgrim]

Need to implement the following for PHP 7 types:

• New ReflectionType class - see http://php.net/manual/en/class.reflectiontype.php
• ReflectionParameter::getType (should return a ReflectionType) - see http://php.net/manual/en/reflectionparameter.gettype.php
• ReflectionParameter::hasType - see http://php.net/manual/en/reflectionparameter.hastype.php
• ReflectionFunctionAbstract::getReturnType (should return a ReflectionType) - see http://php.net/manual/en/reflectionfunctionabstract.getreturntype.php
• ReflectionFunctionAbstract::hasReturnType - see http://php.net/manual/en/reflectionfunctionabstract.hasreturntype.php