Add --keep-raw option to save raw data files

[clintbauer]

Add a -R/--keep-raw command-line option and RawDumps= config key that serializes all collected sample data to a .dat file alongside the SVG, then compresses it with gzip.

[sofar]

The one reason I've never implemented this in the past is that the SVG output practically reads like a raw dump of the data anyway... to me, that is :)

Is there a particular use case that you have in mind for this output?

[clintbauer]

My use case is to support fine grained monitoring / tracking of performance over time.
So items like -

• process 'foo' took 1500ms last month, and is now taking 1700ms
• this week we got a new process 'baz' that has not been seen before
• last month we achieved target 'bar' after 10 seconds, but now we take 11 seconds

Our startups have hundreds of processes, and tracking low level details like these over time needs additional raw data.