This patch provides the following:
* A tree of four exceptions:
```
CurlException
|- CurlHandleException
|- CurlMultiException
\- CurlShareException
```
* Direct aliasing of most functions to class methods, e.g.
 `curl_exec(CurlHandle $ch): string|bool` -> `CurlHandle::exec(): string|bool`
* Remapping of `*_init()` functions to constructors, e.g.
 `curl_init(?string $url = null): CurlHandle` -> `CurlHandle::__constructor(?string $url = null)`
* Promotion of error returning function to use of exceptions where appropriate
* Promotion of certain functions to allow fluent calling, e.g.
```php
curl_setopt($ch, CURLOPT_FOO, "bar");
curl_setopt($ch, CURLOPT_BAZ, "qux");
$ch->setOpt(CURLOPT_FOO, "bar")->setOpt(CURLOPT_BAZ, "qux");
```
* Addition of "last error" functions/methods returning string:
 * `curl_multi_error(CurlMultiHandle $mh): string` / `CurlMultiHandle::error(): string`
 * `curl_share_error(CurlShareHandle $sh): string` / `CurlShareHandle::error(): string`