init: Add init script.
tests: Test that non-files are left alone.
tests: Refactor common bad-start tests.
limitfiles: Fail on any limit count less than 0.
tests: Test correct enforcement way above limit.
limitfiles: Add name to error messages.

This should help diagnose problems if they arise during boot.
limitfiles: Make _common_errnos a class variable.
limitfiles: Cope with IN_Q_OVERFLOW.