---------------------------------
xTN, xTM - Travel Minimum, Travel Maximum
---------------------------------

Defines the maximum extent of travel in that axis. This is used during homing. 
See Homing for more details on how this is used.

Both values can be positive or negative, but maximum must be greater than minimum or equal
to minimum. If minimum and maximum are equal the axis is treated as an infinite axis 
(i.e. no limits). This is useful for rotary axes - for example:

 XTN = -1
 XTM = -1
or
 XTN = 0
 XTM = 0
