Release 0.2.1: Road to options

Added internal curl_setopt wrapper to protect internal state consistency.

Will follow with #9 (internal options state tracking).

Release 0.2: Head[er]s taken!

Added basic support for storing response headers.

Added Browser::getHeaders(): string function to return headers of a recent successful request.

Added CurlException::fromInstance($curl, $previous): self factory method (no more new CurlException($curl) calls).

Release 0.1.2: "Actual PHP8 support"

The code that was using is_resource() in cURL error handling was fixed.
Closes #4

Support for PHP < 5.6 was long since gone. Declaration in composer.json was merely an oversight.

Release 0.1: "Library split"

Split Net\Browser component from the library.