Base: Run WindowServer as a separate "window" user

This was actually rather painless and straightforward. WindowServer now
runs as the "window" user. Users in the "window" group can connect to
it via the socket in /tmp/portal/window as usual.

Base/etc/SystemServer.ini

@@ -22,9 +22,10 @@ User=lookup
 
 [WindowServer]
 Socket=/tmp/portal/window
+SocketPermissions=660
 Priority=high
 KeepAlive=1
-User=anon
+User=window
 
 [Clock.MenuApplet]
 KeepAlive=1

Base/etc/group

@@ -1,8 +1,9 @@
 root:x:0:
 wheel:x:1:anon
 tty:x:2:
-phys:x:3:anon
+phys:x:3:window
 audio:x:4:anon
 lookup:x:10:protocol,anon
 protocol:x:11:anon
+window:x:13:anon
 users:x:100:anon

Base/etc/passwd

@@ -1,5 +1,6 @@
 root:x:0:0:root:/:/bin/sh
 lookup:x:10:10:LookupServer,,,:/:/bin/false
 protocol:x:11:11:ProtocolServer,,,:/:/bin/false
+window:x:13:13:WindowServer,,,:/:/bin/false
 anon:x:100:100:Anonymous,,,:/home/anon:/bin/sh
 nona:x:200:200:Nona,,,:/home/nona:/bin/sh