* Disable serialization and unserialization on classes
Classes that have associated Rust types cannot be serialized for
obvious reasons so these need to be disabled. Disabling these actions
changes in PHP 8.1 to use a flag, so that will need to be solved with
PHP 8.1 support. Closes#97
* update docs stubs
* Rough implementation of struct properties
* Store properties hashtable once
* Tidy up handler functions with exceptions
* Add stub `get_properties` function for codegen structs
* Remove nightly features
* Revert storing properties
Technically, the zend object _could_ move in memory, leaving dangling
references in the properties hashtable. We will just build the hashtable
when required.
* Added `#[prop]` attribute
* Add pointer type to zval, tidy up zend string
* Add support for method properties
* Add `#[getter]` and `#[setter]` attributes
* Update documentation with method properties
* Tidy up macros code
* Remove string gc checks (done on PHP side)
* Move `RegisteredClass` implementation to module, update docs
* Fix read property `rv` segfault
* Fixed doctests
