* PHPC-2219: Prohibit serializing PackedArray as root documents
This adds logic to php_phongo_zval_to_bson_internal() to prohibit serializing PackedArray instances as a root document. Since this function is also used in specific cases to encode a BSON array, a PHONGO_BSON_ALLOW_ROOT_ARRAY flag is introduced to relax the restriction.
* Check if existing field_path element must be freed before overwriting
* Remove function name from Javascript code strings
