* Start work on returning new objects
Change `IntoZval` to consume `self`
* Add conversion from vector reference to PHP hashtable through clones
* `set_binary` now only takes `Vec`
Used to take `AsRef<[T]>` to allow users to pass arrays, however, this
causes the data to be cloned even if the user passes a `Vec`.
* Rename `as_zval` to `into_zval` to match Rust conventions
* Started work on closures
* Finish implementation of closures
* Document closures, add to prelude, feature gate
* Fixed closure example
* Remove uses of `unwrap`, improve library safety
* Started work on `#[php_function]` attribute
* Added `PhantomData` to `ZendHashTable`
Proper lifetimes for `HashTable` type
* `#[php_function]` now accepts `Vec<T>`
Refactored `ZendHashTable` iterators - there is now `Iter` and
`IntoIter` depending on whether it will consume the HashTable or not.
* Add support for nullable types
* Allow `optional` parameter on attribute
* Support primitive and `Option` return types
* Tidied and refactored attribute
* Added documentation for `#[php_function]`
Implemented `IntoZval` for `Option<T>` when `IntoZval` is also
implemented for `T`. `None` resolves to `null`.
* Added `#[php_method]` attribute
* Added `Callable` type, implemented `Drop` on `Zval`
While implementing `Drop`, the `Copy` derivation was removed, however,
this should not have been there in the first place (`Zval` is not valid
for `Copy` if it contains a string).
* Added some macro functions to example
* Add support for boolean arguments
* Added wrapper around binary data
Future support for binary arguments with `#[php_function]` macros.
Unpacking binary data is no longer unsafe. It was never really unsafe in
the beginning, as we were always reading valid memory, just the contents
of the data could not be trusted.
* Added `#[php_module]` attribute, added support for binary arguments
* Added defaults for functions
* Add defaults for methods
* Add startup function macro and prelude
* Refactored method adding
Now done through impl attribute
* Don't rename functions - generate another internal fn
Also hide all generated functions from docs
* Generate startup function when not already defined
* Add support for class and global constants
* Updated `skel` project
* Updated macro documentation, added executor globals
* Remove `Copy` bound for HashMap to Zval
* Updated documentation
* Add `FromZval` trait, updated docs
* Fixed clippy lints
* Fixed ZTS executor globals
* Fix clippy lint
