TODO: removed "HTTPS proxy"

 1.5 get rid of PATH_MAX

 1.6 Modified buffer size approach

 1.7 Detect when called from within callbacks

 1.8 Allow SSL (HTTPS) to proxy

 1.9 Cache negative name resolves

 1.11 minimize dependencies with dynamicly loaded modules

 1.12 have form functions use CURL handle argument

 subsequently can add code within libcurl that returns error if called within

 callbacks for when that's not supported.

1.8 Allow SSL (HTTPS) to proxy

 To prevent local users from snooping on your traffic to the proxy. Supported

 by Firefox and Chrome already:

 https://www.chromium.org/developers/design-documents/secure-web-proxy

 See this stale work in progress branch:

 https://github.com/curl/curl/tree/HTTPS-proxy based on this PR:

 https://github.com/curl/curl/pull/305

1.9 Cache negative name resolves

 A name resolve that has failed is likely to fail when made again within a