extrajoints demos

1extrajoint
   5 joints total
   1 extra joint (joint.4)
   immediate homing
   (jog joint4 before homing to
   create a small motor offset)

2extrajoints
   6 joints total
   2 extra joints (joint.4,5)
   simulated home switches

12extrajoints
   16 joints total
   12 extra joints (joint.4-15)
   simulated home switches