[2.1] Allow to disable mixed rockets

[OMGamerNL]

TL;DR

Add an option to disable the use of the new mixed rockets for a space-platform's imports.

What?

I suggest an option like the "Auto request missing construction materials" to disable the use of mixed rockets for either all or groups of the platform's imports.

This option would be off by default, but when enabled either all or just specific groups of imports sent to the space-platform would use the rocket capacity as a default minimum payload or the custom minimum payload of course.

The option to disable mixed rockets for specific groups of imports would be more flexible and a better option however in the current GUI layout I would not know where to fit it. As opposed to the "global" space-platform option which could fit neatly under the "Auto request missing construction materials" option.

I did also see this similar suggestion about mixed rockets respecting the custom minimum payload. I think this would accomplish the same goal of exact control over the amount of imported items. However having to set a custom payload for each item I want to import, equal to its rocket capacity, seems overly complicated.

Why?

I really like the new mixed rockets added in 2.1 however they sometimes also lead to annoying situations.

When using space-platforms I often have cargo imports that fully or very nearly fully fill the inventory. The mixed rockets can now lead to items being imported slightly over their intended capacity, overfilling the space-platform.

This means other imports cannot be fulfilled and on-platform item storage cannot happen!
Allowing players to disable the use of mixed rockets would ensure that these more exact imports can also be completed, in addition to solving some OCD

[TamTamTam]

I would be fine even with global option to disable mixed rockets completely. But being able to turn it on/off per ship would be nice too.

My reasoning is that they tend to waste rocket if you underproduce one or all of the items you requesting. For example, i requested 50 assembler 2s and 50 accumulators. First rocket sent mix of both, probably because i didn't have enough accumulators, then it sent full rocket of assemblers and then after some time a full rocket of accumulators. Three rockets instead of two, early game this stuff does matter. Also, when you constructing a new ship, it generally send more stuff then you actually need too, and in the end you still have to manually send remaining stuff or fiddle with minimum payload on the platform. Ended up with spillage from space platform hub on my first ship because it oversent. I would just like something more deterministic with rocket requests, reverting to old behaviour suits me perfectly.