fixup! Handle “did-save” bundle item callback in OakTextView
Remove path attributes from document_t
Rewrite proxy code

We now use CFNetworkCopyProxiesForURL() to get the list of potential proxies, hopefully this will perform the proper “proxy auto discovery” (issue #973) though we still need to handle PAC ourself.

Presently we only use the first proxy found, ideally we would try them all (but this will require some API changes).
Convert CFURL → std::string in plist::convert

This is mainly for debugging purposes (printing a CFDictionary).