Custom ranges for temperature overlay

[Buldric]

It would be nice to be able to customize the temperature overlay to effectively map very small variations in temperature.

This could be done by squashing the color scale for the overlay to map onto whatever arbitrary range of temperatures the player provides. Anything outside the given range could be clearly marked with different colors (maybe map "molten" and "absolute zero" colors onto the out-of-range extremes).

Example: the ideal temperature for Mealwood is between 18°C and 22°C. Using the current overlay, it's almost impossible to distinguish such a fine temperature gradient, so we're forced to mouse over each tile and manually check whether the plants are within the ideal range, and how close to the edge they are. With a customizable overlay, even a half-degree difference in temperature would be clearly visible.