set proxyauth to any available to fix corp proxies with windows logins Fix #49

[gwinkless]

Some corporate proxies use windows SSO using NTLM.

libcurl already has support for this baked in, but unfortunately by default the updater only allows BASIC authentication (as per https://curl.se/libcurl/c/CURLOPT_PROXYAUTH.html, the default value is CURLAUTH_BASIC). By setting this option to CURLAUTH_ANY and setting the proxy string in npp to http://:@my.proxy.address/, this Just Works.

Fix #49

[xomx]

@donho
I cannot test this PR myself but it seems to me ok, because then the WinGUP network connectivity should be more universal and safer:

CURLAUTH_ANY
This is a convenience macro that sets all bits and thus makes libcurl pick any it finds suitable.
libcurl automatically selects the one it finds most secure.