A recent update to the AnyConnect server leads to the useragent being checked for starting with "AnyConnect". If the useragent does not start with "AnyConnect" the connection is closed, as reported in #544, #599, and #567. Passing the option `--useragent=AnyConnect` works around the issue, but is not intuitive. Most users will not know about this, and will simply give up. ~~Moreover, it is not possible to pass this option when using the GUI of KDE or Gnome, which most users will most likely be doing.~~ With other words, OpenConnect is completely broken for most users who try to connect to an AnyConnect server with recent updates. Using the useragent "AnyConnect" by default when connecting to an AnyConnect server, will fix this issue.