Synchronize composer.lock with composer.json

This change was effected with the following command:

  composer update --lock
Add `haltDir' feature
Improve check for running process

We are switching to `posix_kill', which is faster, and probably
more portable, than using ps and grep.
Correct misspellings

The main change is to spell `acquire' correctly.
Merge pull request #20 from ruafozy/haltdir-and-other-changes

`haltDir' feature, some fixes, and a minor improvement