GTKUI: Add a separator after Plugins in Preferences

To help distinguish where the plugin pages start a horizontal seperator
is now included after Plugins.
Rearrange the Network tab in GTK and Web UIs

Also applied the suggestions in #2055 including removing 'Encrypt Entire Stream'
and default it (prefer_rc4) to True
Console UI: Fix problem displaying first-run message
Make sure auth file is closed during get_localhost_auth
Add default localclient info to localhost items in gtk connection manager