Allow setting a "production step" so that automatic trims/fixes produce shorter (nicer) numbers

[immerrr]

Usually, one wants their producers to be balanced exactly, otherwise those extra digits after floating point will create blockages at some point. But, when storages/sinks come to the picture, this is no longer an issue, and "allocated surplus/sink" configuration for a given part implies that the extra that doesn't fit in the storage will end up in a sink eventually.

This opens a possibility for setting up a "round up to the nearest Y items/min" or "round up to the nearest X% clock speed" for those parts. For example, if a part has 3.1234/min downstream requirement and 5/min "allocated surplus" (see my suggestion in #46), instead of hunting the decimal digits across the factories, both in the app, and in-game, one may set their production output to 9/min, since there is really not much difference between stocking up/sinking items at the rate of 5/min and 5.8766/min. This will not only help with the production line in question, but may reduce the overhead of tweaking the upstream ingredient production, which may be liquid/gas and not as easy to sink.

[Maelstromeous]

@immerrr To illustrate this better, could you provide a scenario?

Ideally, could you provide a share link with a simple setup of what you're meaning, with the values that currently show versus what should be shown? I understand sort of what you're getting to, to have it round to a certain amount, but the visualisation of that would be rather tricky and some people may want the exact-ness for specific reasons.

The visualisation of "x.xxx amount sunk" is likely going to be part of the solution within #46, and all of the trim / fix production buttons taking this into account.