Copy array arguments if safe in safely_copy_argument_zval_as_scalar

[asgrim]

At the moment array types are turned into the string "array". An improvement on this mechanism would be to descend into the array, and safely convert the array items too (recursively).

This is useful for stuff like Predis\Client->__call so we know the parameters used. At the moment, we'd get an argv of string("set"), string("array") which is ok, but it would be more helpful to convert this to string("set"), array{string("foo"), string("bar")}.