introduce a simple per-algorithm memory monitor for EventLoop

This will **not** be able to detect memory leaks, but instead it will
just monitor how much memory an algorithm allocates during setup.
This allows to see if any of the algorithms has a particularly large
calibration table or similar.

It also contains occasional memory usage printouts during the job.  That
allows to see whether memory gets consumed in the job setup, or during
execute

This is mostly meant to allow debugging some current problems with the
Top jobs which quickly shoot up to 3.2GB memory consumption.