chore: Fix panic when .chezmoidata or .chezmoiexternal did not have a…

…n extension

feat: Re-enable building with Go 1.16

chore: Document more internal functions

chore: Update dependencies

Merge pull request twpayne#1448 from twpayne/source-dir-not-root

Detect when the source directory is already in a git working copy

Add doc on detemining whether the machine is a laptop or desktop

Merge pull request twpayne#1394 from twpayne/fix-1392

Append path arguments to diff and merge command if not provided by user

Merge pull request twpayne#1387 from twpayne/remove

Add remove_ attribute

Merge pull request twpayne#1373 from twpayne/tidy-docs

Miscellaneous fixes

Merge pull request twpayne#1363 from twpayne/fix-keep-umask

Fix creation of .keep files when umask is 002