[2.0.30] No replacement for deleted get_flow() function

[blargh2015]

I'm the author of https://mods.factorio.com/mod/UtilizationMonitorBlargh - a mod that puts percentage used on all items that it can.

Prior to 2.0, I could do this reasonably accurately for pumps and heat exchangers by using the get_flow() function to get how much they were moving through, and use that to calculate the percentage.

In 2.0, there appears to be no way to get that sort of information, or anything related to getting what the UI is showing with (for example) Pumping speed: 590/s of 3000/s.

The 3000/s I can't get directly because pumping_speed in the prototype doesn't have a matching get_* function for the quality - I have a separate thread for that.

The 590/s there doesn't appear to be any way remaining to get it.