Color mixer

This color-mixer accepts 3 types of inputs:

• '?' : random color
• r,g,b: RGB code, where r, g and b are numbers between 0 and 255. For example, yellow would be '255,255,0'
• 'r*g*b*': proportion of red, green and blue. For example, yellow would be 'rg'

It fades smoothly between colors (linear interpolation) and turns red whenever there is an error in the input string.