Simplify directory structure
Trigger command on Return
Rename a function
Refactor
Rename a variable
Simplify event deduplication logic

As a side effect, this also fixes the issue that multiple parallel runs
could be triggered previously. One problem still remains, however: If
multiple events occur during a run, multiple runs in a row will be
triggered.
De-duplicate events during a run

Multiple events during a run should only trigger a second run, not
multiple runs.