Allow specifying intensity of palette colors

[ErdaradunGaztea]

palette_lgbtq() should take an additional parameter or two that would allow the user to modify values in HSV system or something similar (do the research about it).

Values in [0, 1) range would reduce values of the selected parameter, values in (1, Inf] would do the opposite (doing basically the inverse of the former). It would be a simple multiplier.