- Uses the TrapEndcapTracker geometry construction
 - Material thicknesses needs attention.

Squashed commit from Marshall

	new file:   ci_GEM.xml
	new file:   compact/ci_GEM.xml
	new file:   compact/ci_HCAL.xml
	modified:   compact/definitions.xml
	modified:   compact/display.xml
	modified:   compact/materials.xml
	modified:   reference_detector.xml
	modified:   src/cb_CTD_Si.cpp
	new file:   src/ci_GEM.cpp
	new file:   src/ci_HCAL.cpp

	renamed:    elements.xml -> compact/elements.xml
	renamed:    materials.xml -> compact/materials.xml
	modified:   reference_detector.xml