Add "incl. time" column to summarize and perf.rlo

[michaelwoerister]

Many tools show both the "self-time" of an event and the time that also includes the child events. I found myself wanting that feature for perf.rlo in a number of cases recently. Others seems to think the same: #104 (comment).

I think I would prefer the caption "incl. time" for this since we already use the term "total time" for the total amount of time spent in all threads.