Merged gem-geometry from repository bsunanda
GE21 geometry
GE21 geometry
GE21 geometry
Add more details.
Correct constants.
Fix overlap.
Fix overlap.
Update for numbering.
Specs for GE21
Numbering update.
Update for numbering
Fix GEM numbering.
Fix GEM numbering.
Extra details in GE21 long chambers.
Merge pull request #1809 from ianna/gem21-geometry

Geometry updates -- GEM21 geometry