Merge branch 'dev'
Resolved loads of memory management issues.
NSStream postpones delegate messages via run-loop.
NSHTTPURLProtocol is rewritten to have more simple and reliable code flow.
URL-loading system may be considered close to stable, except for shared NSHTTPCookieStorage.
configure: do not use GNUTLS on OSX by default, since it is linked to CoreFoundation; correctly detect OpenSSL