FLEXI_XSERVER: Start a new X flexible server
Only supported on connection that passed AUTH_LOCAL
Supported since: 2.2.4.0
Arguments:  <xserver type>
If no arguments, starts the standard x server
Answers:
OK <display>
ERROR <err number> <english error description>
0 = Not implemented
1 = No more flexi servers
2 = Startup errors
3 = X failed
4 = X too busy
6 = No server binary
100 = Not authenticated
200 = Too many messages
999 = Unknown error
