Quality Promotion

No more Quality RNG! Each craft now advances the progress towards each Quality tier according to what its random chance used to be.

Supports all machines based on Assembler (e.g. Foundry, Chemical Plant) and Furnace (namely, Recycler).
The Promotion panel can be put on the side or at the bottom.
Can be added to and removed from existing saves. The mod does not alter the modules themselves - it manipulates the crafting result.
Compatible with Inverted Quality.
Supports modded Modules and modded Qualities.

Unsupported interactions with other mods:

Beacons broadcasting Quality.
Things spoiling into Quality Modules inside module slots (Quality Modules getting spoiled into something else IS supported).
Anything related to ItemIngredientPrototype::quality_min, quality_max, quality_change.
Anything related to ItemProductPrototype::quality_min, quality_max, quality_change, affected_by_quality.

Mining Drills are not affected by this mod and remain chance-based.
Changing the recipe resets the Quality progress, which is most relevant with Recyclers (scrap recycling is considered 1 recipe). This might change in future updates.
Code was optimized for performance at the expense of readability.
Was primarily developed for and tested on Factorio 2.1; the 2.0 version is a backport.
For modders: the mod creates a remote call interface for marking a machine as potentially crafting with Quality: remote.call("quality_promotion", "mark_quality_machine", luaentity), although the mod also listens for script_raised_built event.

When upgrading Assemblers from Tier 2 to Tier 3, the Quality progress gets lost.