KIO Proxy overhaul part II:

Features:
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* Add SOCKS proxy support to KProtocolManager.
* Add functions for obtaining multiple proxy URL addresses, e.g. PAC scripts.
* Add support for obtaining system proxy information on Windows and Mac platforms.
* Send a new meta-data, "ProxyUrls", to ioslaves with a list of comma separated
proxy urls.

Fixes and optimizations:
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* Compare only url protocol/host/port when comparing proxy addresses.
* Do not bother to lookup proxy information for local protocols, e.g. man/info/file.

REVIEW:101037
DIGEST: KIO Proxy overhaul for KDE 4.7, Part II