Merge branch 'cf/submodule-progress-dissociate'

"git submodule update" and "git submodule add" supported the "--reference" option to borrow objects from a neighbouring local repository like "git clone" does, but lacked the more recent invention "--dissociate". Also "git submodule add" has been taught to take the "--progress" option. * cf/submodule-progress-dissociate: submodule: add --dissociate option to add/update commands submodule: add --progress option to add command submodule: clean up substitutions in script