Inline docs for the develop-version is also located at http://phpdoc.tornevall.net/TorneLIBv5/class-TorneLIB.Tornevall_cURL.html
People sometimes wonder why we are (probably) rebuilding the wheel as others have done this too before, but this library are born from a very old project, that was built for testing proxies scraped from different kind of sites and lists. The first step that was made then, was to build a client that actually could scrape sites without having to set up a whole bunch of scripts and libraries (this happened around 2000-2006 so, in that moment, we did know very little about which libraries that existed). As the source code probably reveals it has a quite big section, just to configure tunnels and proxies in different methods. And this is also why this library exists.
As we was scraping proxies, we also needed to find out how the proxy acted, so there is plenty of time wasted on this. Sometimes for example, when connecting to a socks proxy, we not only flagged the proxy as working. We continued to compare the connection to the outbound connection and if the ip address on the outgoing interfaces was matching the "inbound". If we found a mismatch, this proxy became flagged as an "elite proxy" (which this behaviour is called). We also wanted to scan for proxies which revealed the origin ip by HTTP_VIA and similar headers. In short, there's a whole bunch of scenarios, that we could not get out from a library unless we built it ourselves. So, here we are!
To get the most out of this library, there is currently one dependency to php-xml which makes the SOAP client work. Normally, when starting on an empty machine (Ubuntu), very little things needs to be done to run: