Update changelog

Improve concurrent batch handling with worker groups.

Add config option to control concurrent git operations

v0.4.6

- Add missing error handling.

The absence of this error handling meant that module.prime() would
appear like it ran successfully, but it didn't.

Sync operation must now be explicitly chosen (`dotf sync` no longer s…

…yncs both bare and modules as default)

Errors are now explicitly checked by git's exit status and will kill …

…the process when encountered.

This was tricker to do before, as git also prints non-error information to stderr.

Fixes case where dotf sync is killed when bare repo does not need pus…

…hing

Pass up errors from bare git repo sync

Batch module commands are now killed and have their errors passed up …

…when failing.

Add `dotf m --status` to show status of modules.

If status is clean, no output is printed.