Deprecate gantry.comp

Deprecate the "gantry" HAL component.

Author: andypugh

src/hal/components/gantry.comp

@@ -51,6 +51,16 @@ pin in  float search-vel "HOME_SEARCH_VEL from INI file";
 function read  fp "Update position-fb and home/limit outputs based on joint values.";
 function write fp "Update joint pos-cmd outputs based on position-cmd in.";
 description """
+--- Deprecation Notice 
+
+gantry - Superseded by the general purpose 'trivkins' kinematics module.
+
+To specify a gantry with non-identity kinematics: use trivkins with the kinstype parameter set for KINEMATICS_BOTH. Example:
+
+loadrt trivkins coordinates=xyyz kinstypes=BOTH
+Drives multiple physical motors (joints) from a single axis input
+
+--- End deprecation notice
 Drives multiple physical motors (joints) from a single axis input
 .LP
 The `personality' value is the number of joints to control.  Two is typical, but