modified:   compact/vertex_tracker.xml

Fixed ce_GEM overlap

 - CylinderTrackerBarrel_geo can be used to define detailed modules
 which are then placed in barrel array.
 - The modules are cylindrical segments of a tube.
	modified:   compact/definitions.xml
	modified:   compact/gem_tracker_endcap.xml
	new file:   compact/mm_tracker_barrel.xml
	modified:   reference_detector.xml
	new file:   src/CylinderTrackerBarrel_geo.cpp