This code was actually not breaking most cookie handling by accident.
As the raw cookies where not split properly we added cookies with values like
"key: val; key2 = val2; key3 = val3"
When the code was corrected we overwrote the newer values in the jar with
the old ones from a request.
The proxyAuthenticationRequired() signal now goes to the
ProxyAuthHandler class. That class will try to read the proxy settings
from the keychain or ask the user about them.
We won't ask the user for credentials for explicitly configured proxies.
It also does not change how the credentials for explicitly configured
proxies are stored. (see #261)
