color palette creation helper

Changes for 1.50 - 2023-08-10

• = first phase of of 2.0 rewrite
• + add CMY, CMYK and HSV support
• + new universal getter method: values
• + new modifier method: set, blend
• ~ enhanced and strictened modifier method: add
• \ deprecate all other numeric getter: rgb, red, green, blue, rgb_hex, rgb_hash, hsl, hue, saturation, lightnss, hsl_hash
• \ till 2.0 will be also deprecated: rgb_gradient_to, hsl_gradient_to, gradient_to, distance_to, blend_with
• & new getter API
• & keep complex names like 'SVG:green' to be returned by getter: ->name
• ? rewritten large part of documentation