xyzx_gantry configs using:
  trivkins coordinates=xyzx kintype=BOTH

xyzx.ini          -- includes sim_pin simulation for wheel jogging
xyzx-xhc-hb04.ini -- uses an  xhc-hb04 pendant (18 button model)

Usage:

    1) F1        (estop off)
       F2        (machine on)
       Ctrl-HOME (home, switch automatically to teleop mode)

    2) Teleop mode jogging:

         keyboard jog: Left/Right arrows------ x
                       Up/Dn arrows----------- y
                       PgUp/Dn---------------- z
                       left/right bracket----- x

         mpg jog:      rotary x/wheel -------- x
                       rotary y/wheel -------- y
                       rotary z/wheel -------- z
                       rotary a/wheel -------- none

         sim_pin jog   jog:x-0 +/- ----------- x
                       jog:y-1 +/- ----------- y
                       jog:z-2 +/- ----------- z
                       jog:3   +/- ----------- none

    3) To switch to joint mode in axis gui, use '$' key

    4) Joint mode jogging:

         keyboard jog: Left/Right arrows------ joint_0
                       Up/Dn arrows----------- joint_1
                       PgUp/Dn---------------- joint_2
                       left/right bracket----- joint_3

         mpg jog:      rotary x/wheel -------- joint_0
                       rotary y/wheel -------- joint_1
                       rotary z/wheel -------- joint_2
                       rotary a/wheel -------- joint_3

         sim_pin jog   jog:x-0 +/- ----------- joint_0
                       jog:y-1 +/- ----------- joint_1
                       jog:z-2 +/- ----------- joint_2
                       jog:3   +/- ----------- joint_3

Notes:
a) For simplicity, the configs connect:
       joint.N.motor=pos-cmd => joint.0.motor-pos-fb
   and use immediate homing (no home switch logic).

b) The configs use [KINS]AUTOTELEOP= to automatically
   switch to teleop mode after homing.

c) The LIB:xhc-hb04.tcl script handles configurations
   with known kinematics -- trivkins for the configs
   provided here.

d) For a machine configured as xyzx, the 0,1,2 --> x,y,z
   connections are handled automatically by LIB:xhc-hb04.tcl.
   Additional hal connections to allow jogging joint_3
   are done in a postgui hal file (xhc-hb04-postgui.hal).

   In practice, independent joint jogging of joint_0 and joint_3
   may rack a gantry or cause other problems if not used with
   extreme care.