Without removing postings correctly, it was possible to end up with
multiple workers assigned to a job that workflow had suspended
multiple times, which caused crashes if more than one worker was
assigned to the same job by DF.
This adds an additional command, fix-job-postings, that runs
automatically when loading a world and fixes:
- Multiple job postings that point to the same job
- Job postings that point to a job where posting_index == -1
(i.e. jobs that should have no posting assigned)
Fixes#741
2aeac718cc