Merge branch 'en/sparse-checkout-fixes'

Merge branch 'en/sparse-checkout-fixes'

Further polishing of "git sparse-checkout".

* en/sparse-checkout-fixes:
  sparse-checkout: reject arguments in cone-mode that look like patterns
  sparse-checkout: error or warn when given individual files
  sparse-checkout: pay attention to prefix for {set, add}
  sparse-checkout: correctly set non-cone mode when expected
  sparse-checkout: correct reapply's handling of options