Plot time data anomalies

[Joshua Zivkovic <joshua.zivkovic@xxxxxxxxxxxxxxx>]

Hello,

I've been working on adding JSON and table output to `systemd-analyze
plot`, to allow programmatic access to the data presented in the SVG
produced by `systemd-analyze plot`. Whilst using this data I have
noticed some irregularities in the initialisation times associated with
a variety of units. It seems as though these units are being activated,
deactivated and then reactivated because they have recorded
deactivation times that are before the recorded activation time.

Looking at some of these units, they don't use the `Restart=`
configuration so it's unusual that they are seemingly being restarted.

These irregularities are dealt with by forcing the values to some other
recorded value of that unit through a series of conditions in the SVG
production code.

I'm interested in whether this means that the times for unit
initialisation, presented by `plot`, aren't entirely accurate and if
there is anything that can be done about this.

Kind regards,
Joshua Zivkovic