Merge branch 'ds/feature-macros'

A mechanism to affect the default setting for a (related) group of configuration variables is introduced. * ds/feature-macros: repo-settings: create feature.experimental setting repo-settings: create feature.manyFiles setting repo-settings: parse core.untrackedCache commit-graph: turn on commit-graph by default t6501: use 'git gc' in quiet mode repo-settings: consolidate some config settings