Densitometer application

A densitometer application is included. This allows using any of the supported spectrophotometers as densitometers. Allows setting of paper and solid reference so that true dot percent can be calculated. Allows changing of the Yule Nielsen number to better simulate the media's characteristics. Displays densities for the Black, Cyan, Magenta and Yellow channels. Allows exporting measurements as tab or space delimitted in KCMY or CMYK order.